I am also working in Saudi and I have travelled to qatar before. Tell me what kind of craft he has in Saudi? If he is engineer, doctor, lawyer etc. then it is not a problem and he can get visa on arrival by paying QR 100. I actually went by car and I get the visa on border for me and my family for QR100 each.

If he has some other craft then it is a different story. I have visited the same way UAE, Bahrain, Qatar and Kuwait.