I don't see 'Poor' as an outright problem, but it's definately something to take into consideration if you are striving for killer performance.
My guess is that the high client number is driving the 'poor' status.
It really depends on use case though. If users want to associate and grab email or a basic web page their experience would probably be fine. Concurrent streaming of 4k video... eh not so much!
The scary part about high client association is that ARM functions start to degrade as the user counts rise. The channel scanning becomes less frequent since the AP hardware is busy with users. There's also a threshold (can't recall the exact value) where ARM will stop adjusting channels if too many users are associated. Dedicated AirMonitor's are a good idea for areas where AP's are user-heavy.