I'll be honest - I think your example is contrived and/or a strawman, because you chose a "topic" that already seems to have assumed its conclusion e.g Can we have a "rational discussion" on "The benefit that 2 + 2 = 5"?
> Why should I have a rational discussions..
I think the question here is whether you can censor other people who want to have that discussion, not whether they can force you to participate.
> I'm unsure what possible benefits there are
But you want to veto the topic anyway? It sounds like you want to win the game without playing. To be considered "right" you must bear the burden of the argument.
> Is it wrong to be against a rational discussion of (.+)\?
Yes, it is.
The rest is the discussion why - in particular by pointing out that rational discussion does not automatically imply that abhorrent conclusions will be reached or accepted. The primary thing about rational discussion is that some (or all) participants may be wrong. It's also the difference between discussion and shouting through each other.
> Why should I have a rational discussions..
I think the question here is whether you can censor other people who want to have that discussion, not whether they can force you to participate.
> I'm unsure what possible benefits there are
But you want to veto the topic anyway? It sounds like you want to win the game without playing. To be considered "right" you must bear the burden of the argument.