Indeed, monitoring the RSSI/RX state with the threshold set to 200db we are constantly woken up by noise (no moteino transmitting). With RXTIMEOUT2=75, I see RSSI last about ~35µs (though sometimes almost a ms!), and RX is consistently around 340-370µS. I never see the timeout bit set in this scenario. If I set RXTIMEOUT2=0 (disable the timeout) the results are dramatically worse, and we spend about 24ms
in RX. If I set RXTIMEOUT2=1, the results are similar to when it's set to 75, but I do get the timeout bit set. It seems like there is a minimum RX duration that cannot be shortened by using the timeout interrupt. That doesn't really explain why the timeout bit isn't set at higher values, though.
In any case, setting the RSSI threshold to 170db seems to avoid waking up from the noise in my office.
EDIT: I forgot to mention, if I listen at 5.5kbit there are significantly fewer wakeups at 200db. Same results otherwise.