You don't like it and you mock the Baathists because you consider them "fake nationalists". That's all.
Not necessarily Baathist(although I don't like Baathists overall, but thats a different matter). But Assad and his sect. You know they did a coup inside the baathist govt right? The guy he overthrew to take power was also a Baathist.
You see they want to preserve their rule, and if they can't rule over, they themselves, many of them will call for seperatism, if they themselves are not in charge.
I've seen it on twitter, quite a few Alawite Assadists calling for a breakaway state in Latakia and Tartus under the protection of the two Russian bases, when only a few weeks back they were projecting themselves as "Syrian Nationalists".
See the difference?
Under this context, there is no issue with supporting another group that is also a threat to the territorial integrity, b/c thats your own backup plan anyways.
So Assad tactically supported them against other Syrian(syrians under the majority btw), b/c he saw them at the very least as a tactical tool. And if he was successful in destroying his main opponents, then he could think about taking out the separatists he created, and if he wasn't successful in taking out the other Syrians(majority), the separatist entity is still an ally in a power balancing scheme, whether in a stalemate freeze, or in a permanent breakage.
When you understand these axioms, you understand this conflict and his tactical play better.