If Marco Rubio wants to run for anything he can. All he needs are votes.
If you say he is ineligible you will have to prove it in a court of law.
Until that happens he can do what he wants.
The courts have (and probably will not) ruled on Obama ....he is therefore eligible to be President.
correction:
The courts have not ruled on Obama (and probably will not) ....he is therefore eligible to be President. In fact he is President ....a terrible one but still a President