He loses the chance at an 8th year if he goes to July 1st.
If he's going to re-sign with the Islanders, if anything he's idiotic going to July 1st since he'll then re-sign with them anyways for 7 years instead of 8.
The only reason he'd go to July 1st is if he didn't want to re-sign with them. If his first choice is to re-sign, then it makes zero sense to go to July 1st.
If he's curious about offers, he can just wait for the interview period from the draft until June 30th or whatever to gauge interest. But unless he's absolutely 100% convinced he's leaving, it doesn't make sense for him to become UFA.