After being clued in by alert PTR members, I'm becoming suspicious that Zach Collins was A) following a set play, B) executed the set play well, and C) was rewarded by Pop, resulting in the "dap" and eventually the team win. From a basketball standpoint, trading Collin's expulsion for MPJ's expulsion is a win all the way around for the Spurs. MPJ plays an important role for the Nuggets, but has a temper. Collins cleverly took advantage of the temper to give his team an advantage.
When you watch the video, MPJ clearly taunts Zach, who was simply contesting the shot as he should be doing. Until the referee blows the whistle to give MPJ a technical, Collins is cool. Once he knows MPJ is going to be "T'ed up", he charges towards MPJ, and bumps him. MPJ foolishly grabs Collins by the throat, which is likely exactly what is anticipated in the Spurs scouting report. Mission accomplished, Collins immediately backs off without any further issues.
Collins and Pop calmly watch the replay video, and Collins goes back to the locker room with his mission accomplished. Denver is denied a strong 3 point shooter, who is a legitimate "3rd Banana" for a Championship team. Excellent execution.