The checking is to be done by the airlines before boarding on behalf of the Thai authorities. So contact your airline and ask them if they will accept Johnson and Johnson single shot.
It is weird they have sent it directly to the airlines. Quantas and Turkish updated their travel advice but not NZ etc as yet. Yet it will affect long haul flights departing tomorrow.
It's a nightmare for those already booked for January. There is a small window for refunds for accommodation and covid travel insurance doesn't cover change in vaccination policy.
Read ALL this article from Bangkok post today. It says all countries will be treated the same and mandatory vaccination is one of the things being considered.
Unfortunately not, they are going to treat everybody the same, whatever they decide. They are considering whether to bring back jabs for all. We should know by tomorrow.