The short answer, you will get kicking in the head.
The long answer, you're sticking your chin out. It takes all of your core out of the punch and takes away all of the power. If you bend over like that guy from TUF you lose everything off your punches, not to mentioned you will get clinched and get your face kneed off.
I have very bad posture, is there anything I can do to fix it? By the way, stay tuned for a new video I'm about to leave for the gym now.