(I'm posting this answer mainly because I think the posting has missed a very important aspect of the exchange of views that's alluded to in the posting.)
One user pointed out the fact that [the symbol requested by the OP] resembles the swastika ... and [that] he will not teach how to construct such [a] symbol on TeX.SE.
In my view, a very important aspect of TeX.SE's appeal as being a successful and (I hope!) welcoming site is that it's remarkably free of trolls and other types of vermin. This is not just some happy accident.
It certainly helps that all postings that are clearly inappropriate (e.g., vulgar, off-topic, spam, etc) are quickly identified and removed. Importantly, the community itself takes the lead in removing queries that they deem to be inappropriate.
In addition, I'd say that this happy state of affairs also owes, in no small part, to most answers being structured in a way that doesn't attract trolls and other undesirables. And, yes, the desire not to attract trolls can prompt a decision not to post an answer in the first place. If would-be contributors of answers didn't apply some restraint and wise judgment, TeX.SE would certainly be nowhere nearly as successful and welcoming as it is now. For me, that's far more valuable and important than teaching somebody how to draw a symbol that looks like a swastika. Aside: Does the world really need still more instructions on how to draw symbols that look like swastikas? Surely not!
Has TeX.SE or SE some policy regarding such contents?
I don't think it's either necessary or sufficient to formulate a site-wide policy regarding what's entirely inappropriate. Letting users (especially experienced contributors) apply good judgment should be the first line of defense. Happily, to date letting the community apply good judgment seems to be working remarkably well. If the community didn't uphold and enforce standards of decency and fair play, then imposing the policies you seem to have in mind will have come too late: most decent users will have already left the site for good. I, for one, certainly would leave and never come back.