Sure, I see no reason an author should not vote for themselves. If you vote only or mostly for yourself, then that is a problem.
Mostly people get envious with those having more SP and think that for some reason those that have invested in the platform and themselves should not be able to vote for their very self. This really is a nonsensical argument, regardless if you have a penny vote or a $2,000 vote. Whatever size it is, it is because of the investment you have, period!