It depends on the following …
Just get married, file an I-485 package. For good housekeeping you can include the I-129F receipt and a note to cancel the I-129F.
According to my read of https://fam.state.gov/FAM/09FAM/09FAM040210.html practically speaking no.
Per that link, it seems H2-B is not dual intent. So once I-485 is filed, leaving the U.S. means I-485 is canceled. And because he has expressed immigration intent, his H-2B visa is at a high risk being canceled at the port of entry.
He can file I-765 and I-131 to get a work permit and travel document (advance parole - AP), with I-485 but these take over a year, usually. Once he departs the U.S., and enters on his AP, his H2-B status is gone. He would then have to work using his I-485-based EAD.