If company A allows him to go back in December, there's no problem.
It's not a problem to the USCIS because OPT is not employer-specific. The problem is that company A might not hire him back for just one month.
If company A does not notify USCIS to revoke the approved H1, you still have the H1 number to start an I-129 F1 to H1 COS before OPT expiration.
It's not a problem to the USCIS because OPT is not employer-specific. The problem is that company A might not hire him back for just one month.
If company A does not notify USCIS to revoke the approved H1, you still have the H1 number to start an I-129 F1 to H1 COS before OPT expiration.