he'll be okay as long as he makes sure he always sits on the customer's side of the bar. Then he can just be an investor and have Thai staff do the work.
each to his own of course but for me it isn't worth paying 30,000 baht to someone for doing this:
Drive to Central Plaza and go to my bank and ask them for a bank statement. Wait 15 minutes. Told to come back in 1 hour and pick up the letter and statement.
Stroll through the air conditioned shopping center and go to my favorite restaurant and have a nice lunch.
After lunch walk for 5 minutes back to my bank and pick up the statement.
Get in my car and drive to immigration and wait for about 15 minutes before I see someone to whom I hand my passport a form with my signature on it and the letter and bank statement. "Just sign it sir. Don't bother with the form we'll fill it out for you"
20 minutes later pick up retirement extension stamped in my passport and go home.
It costs 1,900 Baht for one year to do it yourself. Why on earth are you thinking of paying someone 30,000 baht to fill out a couple of forms and provide a bank statement!
it worked for me about 8 years ago and then I traveled to the UK and came back and the next time I tried it it didn't work and it never has done since. When I mentioned it to an immigration office he just shrugged and laughed. The new system is also failing many people. It's hit and miss.