I'm surprised you, and your company, did not consider this. Would it not be part of due diligence?
I doubt he will see it that way.
Today you are about an "onboard experience" but tomorrow you could change to transport. Why would he allow you to put your foot in the door?
Why would he accept the loss of even 1 baht from a passenger that may have flown to Samui, but chose to sail there, because they could?
Leasing planes is not cheap, and they have to have a high booking rate to be profitable, more so now, with the higher cost of fuel.
Some of the wealthiest Thai's, and successful Thai companies, got to that position through monopoly, and not by acquiring, but by using connections to halt their competition.
I wish you all the best. I am all for variety and choice here. However, if the project is allowed to go ahead, you can be sure it's only because it benefits such people, either directly, or indirectly, and possibly corruptly, also, and most likely on an ongoing basis.