i think the reason they didnt go after him was strickly cause he was too strong, we already learned that yoda and him were an even match, but i think that both of them were sooo far ahead of obiwan that having him there wouldnt do anything, it was like when mace fought pali haveing 4 council members didnt help it was still pali vs mace after about 2 secs, same would have obiwan would have been killed really quickly and so it wouldnt have mattered is my guess.