(1) there's a lock out, they can't legally (2) Moving that kind of volume at market price is extremely difficult (3) This disclosure was required by law as part of their earnings. They would rather have said nothing and quietly offloaded it.
One consequence of booking the revenue is that they're going to have to report a loss when they sell it.
It's possible there's some tax shenanigans at play (idk): report the profit, mark it against their massive AI capex, sell later when they can book a loss. (I'm not sure if it works that way, it wouldn't for an individual, but maybe they can find a way to trigger a stepped up basis.)
Retail doesn't really move stocks like Google too much, and institutions might understand Google and it's finances better than Google...i.e. there are no accounting tricks or mysterious losses that can shake institutional analysts much (besides illegally hidden stuff). They will perfectly understand why Google is taking a "loss" on the sale.