Guide/Outfitter can say whatever he want's, but whatever scope might be "Ideal" for his "Specific" territory, does not qualify in others, so should you buy something that is suited for just his area? I've carried my 4.5x14 50mm Leopold on quite a few hunts ranging from Mi, Argentina, South Africa, Botswana, S.D., etc... and all I can say is any fault anyone can find with a 50mm is nonsence as far as I'm concerned.
From my experience good guides make due with what you bring and have success, bad guides talk smack and look for excuses.
Don't mean to go off, but I have a real distaste for guides that critize clients.