Failing to defend, failing to adequately resource a defence of even the blindingly obvious can lead to some odd outcomes.
Personally I hope for a pro bono, well structured "piss off, this is stupid" line of reasoning from history. Ask yourself why "AirBnB" chose the 3 letter form in the first place. Thats .. prior art, a generic, or a combination of the two.
(not a lawyer. Hence my doubts this is as straightforward as I personally would like)
N_Lens•2h ago