I think players should be truthful in their self evaluations, perhaps backed up by official bridge league rankings. I frequently play in speedballs on bbo. What I don't like is people purposely falsifying their credentials. I see people who classify themselves as "novice," who end up playing a lot of artificial conventions, I also don't like people considering their rank to be "private." This kind of gamesmanship is inappropriate in competitive bridge.
I'd allow the claim if trumps are 2-2 or the Q falls singleton. Declarer isn't allowed to guess which side may be void, even though the K of spades is correct first play.
I know I'm in the minority, but I bid 5h, especially at imps. This is not a slam try, and partner should give me a lot of space for making a pressure bid. I don't like my defense against 4s. My 5h bid could cause them to go up another level, in which case my double is more to my liking.