P2P's are supposed to be able to speak in the f2ptwink chat, there's just an option to block messages from lvl 1's, 2's and 24's (and this option can be toggled off.)
I think your issue might be some sort of error within the addon itself (since your p2p is lvl 20?). Multiple p2ps have experienced this issue, including myself, and what fixed it for me was either /reload or, if reloading didn't work, re-installing the addon.
I'm not too sure what the actual problem is, and I hope someone more knowledgable than me can shed some light on this problem.