The "Advice" class ability describes itself as identical to bardic performance, the question for me is whether the Sensei qualifies for the feat Extra Performance. I think by RAW it might be "no", and I think by RAI it might be "yes".
RAW, in all likelihood, no. But if it functions just like Bardic Performance, I can't imagine any balance issues arising from reskinning Extra Performance into 'Font of Wisdom' or some such for use by the Sensei.
Though it pains me to say it, I think the intention is to remove all bonus feats after level 6 (inclusive); as the written version apparently assumes that bonus feats are given in 6 level intervals (similar to cavalier and the like).