Obviously, SE gets you one entry (enter within 90 days of it going into your passport) and ME gets you unlimited entries (enter within 6 months of it going into your passport).
The 2 entry limit refers to visa exempt entries by land. Both SETV and METV give you a 60 day stay per entry which is extendable once per entry for an additional 30 days, which you do at Immigration for 1900 Baht.
Just read the original post carefully. All listed requirements were fulfilled, he was asked for an unlisted requirement for Non-O extension for taking care of half-Thai child, for which he has legal guardianship by a court order.
Non-B would be dependent on the sponsor - end the job, no right to stay. He already knows he qualifies for the Non-O, it’s not his first and the rules haven’t officially changed.