I understand your situation, but it's not fair if some teams lose against a forfeited team and others recieve 3 points without even playing against them. The most fair thing to do is give everyone a def-win or remove all the matches of the forfeited team.
About the penalty-points, these points aren't used as map-points. When a total of 8 penalty points is reached, the team will be disqualified. So all teams that aren't active, will be ruled out.