Actually, I have never sent the watches I bought there to another watchmaker to check. But the way I look at it is..
1. he gives you a sale receipt showing the watch model and serial number.
2. he also gives a 2 year warranty for his watches, stated on the receipt.
3. he and his father's shop has been in business for decades with a very large customer base.
I don't think it would be in his best interest to sell fakes. In a small town like Kuching, he and his business would be very short-lived if he tried to do that.
However, condition of watches is another matter. Some could be over-polished and not obvious to the trained eye. His father services Rolex for most of his life but whether he has access to genuine parts, I wouldn't know. I have not had to service a watch yet but if I do, I'd probably send it to the RSC in KL.