Not long ago Turkiye and KSA relations were scarred over Kashogi episode, but due to changing Geopolitical situation, mutual interests and need of hour these countries came together to sign a agreement that attack on one will be considered attack on the other when activated, that's a big development in itself. No permanent enemies or Friends in Geopolitics, only mutual interests and money that define such agreements. Iran war has disbalance the regional security apparatus badly, everyone in the region and outside are back to drawing board, drones change the nature of warfare, Nuclear weapons are becoming less and less scary, and proxies are seen as outdated methods of countering your enemy, there was a time whenever everyone used Proxies, Pakistan did, KSA did, Turkiye did, Iran famous for it, America OG proxy user, Israel did everyone used some useful idiots for their own personal gains and later discarded like a used condom, Houthis/Taliban/PKK/YPG/Jandul Allah etc.
None of the 3 countries will have any thing to lose here but some kind of gains, agreements/defense coorportation between KSA-Turkiye-Pakistan exists before this agreement, investments in local economy was happening regardless so I don't see the fuss regarding a agreement which none of the 3 countries said against anyone, as for why its not activated because of Houthis attack, I think it was @TheSC who said few pages back, it wont be activated after every Houthis missile strike or every PKK attack or every BLA/Taliban attack those are proxy/internal issues which all 3 countries are more than capable of taking care of, if these three countries increase in diplomatic support to each other that will definitely help, Pakistan don't/won't need KSA/Turkish soldiers to charge at Indians in case of a war, as long as we are getting shipments of missiles, ammo, oil and diplomatic support from the 2, we are good and can handle India ourselves.
KSA can hit Houthis and even Iran as Iran AD is pretty much gone beside hitting some drones in recent weeks/months, KSA will get training, more Pakistani troops which will keep an eye on Israel and other countries, while KSA can use its AF to hit Houthis. Houthis are in same position as Taliban, they are already in stone age, and masses of uneducated Jahil people who knows nothing besides war and conflict, its not like Houthis are producing Doctors, Engineers, scientists, professors who are taking arms.. Sooner or later the Yemen own's govt will gain some upper hand and start pushing the Houthis, it will then be either make peace of yet another bloodshed between Yemenis, the point here is that if you see the situation of Houthis, then see what and how Qatari/Kuwaits/Emirati's are doing that should tell you everything, Iranians are using Houthis as useful idiots by sending them their IRGC advisors but that is keeping Yemen in a collective and constant loop of extremism, poverty and even if war with KSA stop they will still suffer because of the sanctions, no one wants military aged men with past fighting experience in their countries, Yemen needs to end this cycle... they need to think about their own people, their own national interest...
As for Turkiye, well PKK/YPG is pretty much non-existent now, Turks did wonderful job with hitting them, not only that they effectively end Syrian civil war, rebuilding Syrian armed forces, slowly but steadily. Turks can fight, they have resources, they have economy, they have technology and cover from major EU/NATO powers, KSA/Pakistan often get denied western Technology, Pakistan-China both now have China and EU alternatives from Turkiye and Chinese rising defense production. In fact Turkiye can diversify its own defense industry by setting up factories in Pakistan-KSA which will help them cover the cost of expensive major weapon systems like KAAN/Subs/Ships/AD, the benefits are very much as long as all 3 countries remain true and honor this agreement.
Lastly, like I've said many times... its too early to say what this agreement will bring, but signing it and starting a process is indeed a good step in right direction, if others join then good if not then i don't see any issue with that, in Islamic world KSA-Pakistan-Turkiye-Iran-Egpyt are the only countries that matters most because of its size, economies, military power, diplomatic power and location. Iran is already taken a beating and they will be licking their wounds for 1-2 decades if they survive (i hope they do) and Egypt well not sure how and where they stand, its too early and right now Egyptians maybe calculating their options, I am not gonna say that countries/leaders just make such decisions out of the blue, there is a whole country with its beaureucracy, think tanks and top minds that sit together and then such decisions are made, so when people make fun of this agreement and call it stupid, and even if we argue that Pakistani policy makers have not made many good decisions in past, I doubt that Turkiye or KSA will just buy this manjan or Churan that Pakistan somehow able to sell it to 2 strongest economies and regional powers, and if we (Pakistan) are indeed that smart that we somehow scam these 2 power houses into this scam agreement, then I would say take a BOW at the Pakistan's foreign policy even if it means they bring these 2 other countries into a sham agreement.