Alarming for bounty hunters? I see no. There are been ICO's in the past who not rely purely on Facebook in terms of advertisement. Yes it's a big help but overall, there are lots of means to spread their respective ICO's , not just in Facebook. If all about bounty thing, the percentage of rewards for Facebook bounties is not that much so a removal of it will not hurt bounty hunters. While on the other hand, if looking at the impact of advertisements, just look in the past where ICO's exposure is not that present much in Facebook but still some ICO's became success.

And aside from that, there are ICO advertisements in Facebook that isn't good to be true. It will just lead for misleading information and conception by people about the project. So for me, that will be a good move by Facebook.