There is no “opt” visa it’s “optional Practical training”. It’s for a limited duration after he graduates also the rules are sketchy if he Would be let back into the country if wants to travel home to see family . If the employer wants to continue his employment he has no choice but to go on H1b. And then H1b has its own requirements and problems with it. Try to understand a lot of people “abusing” the system have not other legal recourse to keep their lives going.