Exchange btc with PayPal is high risk except well trusted member. PayPal could dispute until 180 days. Although he is Sr. Member but its still not enough to deal with PayPal. Obviously who will deal he will do his own risk. On the other hand I don't think any escrow will involved with PayPal deal.
And your point is? 
Sign a message really doesn't mean he is trusted. Sign message means he is the original owner of this account.
Which part of my post conveyed that signing a message means he is trusted? No Shit Sherlock.