I don't think your 'friend' will be able to board at JFK without the CoE.

"He’s contacted the embassy and they’ve confirmed he has been approved entry to BKK. Still no COE has come through."

Not sure what to make of this? Contacted? How? Confirmed? How? Obviously check Spam folder.

Maybe search through some FB groups? One example: Thailand Visa Advice - And Everything Else

Keep calling, staff are said to be working remotely at all hours.

Did see this post this week...

https://forum.thaivisa.com/topic/119...mment=16103836