Maverick was just a generic cipher in a costume that Jim Lee invented for X-Men #5. His backstory (such as it is) has been fleshed out since then. Over the past seventeen years in comics, Maverick has rarely either possessed or used his powers anyway. So Gun-Fu is pretty accurate.
I'm pretty sure that's just bull$#!* someone posted online. The only confirmed Deadpool ending is the one where Deadpool/Weapon XI's dislocated arm walks over the rubble like 'Thing' from the Addams Family and rubs his own dislocated head.