It's what state you declare you are a resident of that matters.
"Matters" for what? His question is whether or not his moving to Philadelphia will violate his contract with Jacksonville for the house to remain his "primary residence" for the next 2.5 years. It's doubtful that merely "declaring" his domicile to be Florida will result in a finding that his Jacksonville home is his "primary residence," when he is in fact primarily living in a different house in a different state.
But what is the definition of "primary residence"?
We can all guess at the answer, but really that is the question that should be posed to the attorney that Jespah suggested the OP consult.