It seems that UMNO has serious problems of money politics or corruption according to this article in malaysiakini Ali Rustam calls for calm, to appeal decision.
I really do not know the extent of vote-buying in UMNO but it appears that preventing anyone from competing for top posts does create opportunities for vote-buying as candidates have to secure a qualifying number of nominations to contest.
It creates two levels of buying votes - first for nominations and then for the actual contest.
With such a system, the candidate with the biggest war chest can buy his way into power and the untold wealth of leadership.
I don't want to get into the details of this case but it appears that UMNO is operating beyond the laws of Malaysia as far as corruption is concerned. Instead of merely issuing warning letters and barring members, it would be good if their disciplinary committee had also stated that they were forwarding their evidence to the MACC and making a corruption report for further action.
In fact, the AG's office should be asking UMNO for the files so they investigate further.