I've never heard of "on point" being used to mean "attractive". That doesn't mean that it isn't used as a slang term with such a meaning. Maybe it's slang used by a group that I am not a member of. In real life, there are a million slang terms for "good", "bad", and "pretty", with new ones being invented all the time. Trying to keep up with the slang of teenagers or other cultural groups would require constant, concerted effort.
And by the way, efforts at compiling "slang dictionaries" routinely struggle with the problem that slang changes constantly and is often very localized. Just because you heard one Ruritanian teenager in Hoboken use a slang term doesn't mean that it is a term routinely used by other teenagers or other Ruritanians or that anyone will still be using it in 5 years. So when you tell me that someone said that "on point" is a slang term for "pretty", I wonder, "by whom?", "where?", "is this used by millions of people for many years or by ten kids in one school for one semester? Etc.
Unless you're in a group where "on point" is routinely used with such a meaning, I think few would even be aware of this meaning.
I am tempted to say that if you are in a context where a phrase has a well-known meaning, no reasonable person would suppose that you were using it with an obscure slang meaning unless that was clearly called for by context. Like in your example, if I was listening to a debate and a woman made a logical argument, and a man said, "Yes, Miss Jones, you are really on point there. That argument clearly leads to the conclusion that ...", I can't imagine that I would think of some slang meaning. Sure, if in the middle of a formal debate a man suddenly said to a female debate, "Yeah babe, in that tight dress you are really on point. Wow.", yes, that would sound like a sexual comment. And I have trouble imagining someone saying that in a debate, but whatever.
But that said, there are people who go out of their way to be offended, who work hard to reinterpret innocent comments as sexual innuendo or racial slurs or whatever. So yes, one should be careful when a phrase can have a double meaning.