I think it makes absolute sense to be an airdrop based on reputation instead of SP, otherwise it would penalize too much the smaller accounts (which are the majority) not attracting so many users to Byteball.

They only qualify B´s that have a decent price because, just like STEEM, if the price is at $1 there is a lot of uncertainty and they don´t want to be responsible for someone losing his investment, that's why they recommend STEEM at $6 and not at $1. Just like all of us, they don't know what's going to happen to crypto.
But I agree with you, it makes no sense.