We have sex but you can't ask about Kama Sutra here either!
But this is a good question that I would like the community to help us moderators with, because I don't know what the difference between philosophy an apologetics is when it comes to this site. We've said for a long time that apologetics is on topic, but always said "general philosophical question" and I don't know how much more general philosophy you can get from something that is taught in every philosophy 101 class.
There is another site to ask [site:philosophy.se] questions, we don't often migrate there though, you're not apt to get a Christian answer either.
But in general, the tag is a noun describing the question. If the tag were anything else it would be a meta-tag. If you tag philosophy you don't make the question a philosophy question, you make the question about philosophy in general. Similarly you don't make the question an evangelism question, you make the question about evangelism. "How do I evangelize in this particular case" is not a question about spreading the Gospel it is a question about how to spread the Gospel.
Furthermore, I've always thought that question about distinctly Christian philosophies (like the Natural Moral Law) were on topic as long as they were Thomistic, not just Aristotelian, I've gotten a moderate amount of pushback on that view and had some questions closed when they weren't clearly on the subject of Christianity, I appreciate that and won't try to foist it on the community just because I'm a mod and a Catholic. I don't really know if there is an Evangelical or Reformed philosophy outside of the Bible, I suspect not.