As the owner of every team in the league and the league itself, McMahon is able to enforce clauses like this, and he intends to do so.
"We are evaluating a player based on many things, including the quality of human being they are," McMahon said. "If you have any sort of criminal record or commit a crime, you aren't playing in this league."
This could preclude some players that have been spurned from the NFL, including Johnny Manziel, from playing. Manziel was arrested for three misdemeanors in 2012, which were disorderly conduct, failure to provide identification, and possession of a fictitious driver's license. Manziel plead guilty for the failure to produce, while the other two charges were dismissed. A myriad of drug related issues have also followed Manziel throughout his career.
Tim Tebow, of course, has no such record and would be allowed to play. Tebow's last time on the field was in 2012, when he played for the Jets. He attempted only eight passes that season, but played in 12 games.
Colin Kaepernick would also technically be allowed, but McMahon has taken a hard stance on players standing for the anthem and attaching Kaepernick's name to the league (even if Kaepernick would theoretically stand) may be a look McMahon would rather avoid.
"People don't want social and political issues coming into play when they are trying to be entertained," McMahon said. "We want someone who wants to take a knee to do their version of that on their personal time."
With the NFL having such an outrageous turnover rate, there will be no shortage of players to choose from. Manziel, Kaepernick and Tebow would be three of the biggest names to attach to the league. However, out of the three them, only Tebow seems like he even could be on McMahon's radar. Now try to imagine Tebow during an XFL game.