For every vote of ‘present’ instead of ‘no’, there are fewer ‘yeas’ needed.
100 Senators. One votes present, you now only need 50 votes to win, not 51 (50-49, I’m ignoring that ties are still wins). Three vote present, a score of 49-48 will get you the win.
A Present vote doesn’t really help, but it doesn’t hurt either.
Not helping is the key. A present vote is closer to a no vote than a yes vote.