The block, if it ever happened, would more likely be on the old transactions instead of addresses actually in order to make a ban database that is small and efficient.
It could be done with a protocol change that would require everyone to update their Bitcoin 2 Core client instead of just recommend to do so like usual.
Keeping Bitcoin 2 fork airdrop intact may still be worth it, all things considered, because not everyone who claims will dump, even though free coins are indeed more likely to be dumped than researched and saved.
There's always a chance that one of those who take their time to claim become a supporter of the project as has also happened in the past.
The total amount of BTC2 claimed from the fork and then deposited to crex24 for dumping/selling during the past few days is way higher than normal. (Around 1800 BTC2) but still nothing too major yet. It just had a major effect due to there being so few people trading BTC2 on a daily basis. Will be interesting to see if this goes on for a while or if there's nothing left to claim by him/them.