No, do not drop him. Mota has really good stuff and in my opinion, should end up closing sometime. To say that he is a bad closer is not exactly a strong argument, because the sample size of the time he closed is too small.
I also do not trust Todd Jones to keep this up at all and once the Marlins generate more save opportunities, he should begin blowing some. As long as Mota's healthy, he has the stuff to be dominant.
The only real worries I have about him are:
a. injury risk because he pitched a LOT of innings the past few years...he might be pitching hurt
b. the little feud he has going on with McKeon...that sure as hell won't put him in a positive light.