To be honest I think some people might get offended not only by your definition if it, but by the fact that you HAVE a choice. You do have sexual urges, but you choose not act on them etc. A lot of asexual people (not all, a lot are content with the way things are) probably wish they could have these feelings are they are such a big part of our culture, of relationships etc., so I imagine for some people they can get offended by this, that you sort of "throw away" what you have and take on asexuality as an identiy when for a lot of people, it is something they have struggled to come to terms with. And I can't blame them, it IS a bit offensive of you.