Personally it depends on your relationship with the rest of the league. Technically yeah it would be fair to keep the money. The only thing really confirmed and un-effected by all this is who won the regular season. That being said I could imagine some people in some leagues not being happy with only the commish taking home money. If someone else had finished in first and settled things did as you mentioned above I’m sure you would get little to no push back over it as it is the right this to do. Only thing is that you are now making a new rule to settle the leagues finances which fairly but coincidentally result in only you making money. I would send a message out to the league telling them what your leaning towards doing, explain why your doing it (first place is already decided) and then say you would follow the plan mentioned above if it was another player in first. Hopefully they understand but if they are very against it you may also want to consider bitting the bullet to keep the peace for future seasons.