In cases with poorly behaved NATs it'll start with a TCP connection to a node willing to relay a packet to a friend. Then it'll attempt to hole punch to reach y

In cases with poorly behaved NATs it'll start with a TCP connection to a node willing to relay a packet to a friend. Then it'll attempt to hole punch to reach your friend/peer. I'm not sure I'd call it cheating but I assume that's the same thing you're talking about. Both clients need to attempt to connect to each other to get udp nat hole punching to work. So I guess yes? If it can't, it will fall back to TCP and relays, so it will totally cheat using relays if it has to :)