You need it in the definition if you want to claim it as such. If cyanide strawberries were found in nature they would be part of the definition of a strawberry, and claiming otherwise would be silly.

Generally speaking what may seem obvious to you may very well not be. I could claim that donkeys are fish, and should you complain that nowhere is said that, I would reply “that’s because it’s obvious”. Not the best of arguments.

If sexual orientation is the classification of what you are attracted to then men, women, everything in between, kids, horses and warplanes are a - semantically - “valid” sexual orientation.

As for harming LGBTQ+ I disagree with that. Whenever someone says “I don’t care who or how you fuck” they generally add “as long as they are consenting adults” - clearly it’s not that obvious.

With this said I think I did my best to make my case and I do not think I can do more if this is not enough, so I will disengage from further discussion.