It doesn't matter if the person using PayPal will go first. The moment PayPal user receive coins he can reverse transaction, defectively scamming his trading partner.
IIRC charge back option for PayPal users is available for 180 days - so this is the period of time you need to wait until it will be certain that transaction won't be reversed.
This is why there should be a holding period in place so this doesn't happen.
Even if they did want to do a dispute of the funds they have up to 180 days to do it but they are risking their paypal account (which is likely a false one anyways
) so it doesn't really matter.
Just get the funds out of there as quickly as possible.
Deter those that try to scam is the only way to deal with these sort of people on these forums.