It’s true that Men’s Rowing isn’t an NCAA sport, but it’s not true that they don’t have restrictions. Men’s Rowing programs are members of the IRA (Intercollegiate Rowing Association), and their members are bound to a number of NCAA bylaws, including all of the Recruiting bylaws. (Source.)
And yes, your student can reach out any time, but the coaches can’t respond (“converse”) until June 15 after their sophomore year.