They're blowing a lot of hot air. DJ's situation is a little different due to his exemption as are any major event winners.
But, here's the key.
It's written in the by-laws of the PGA if a player chooses to resign and plays in competing events he's eligible to return to the tour after sitting out a year. Very specific language, "shall be entitled to..."
So with DJ he's got his five year exemption from winning at Augusta. After that he'd have to sit a year but then it entitled to rejoin the tour.
All of this "we'll ban them from playing" is bullshit. It's a direct contradiction to their own bylaws.