Hmm, personally I think your client should capitalise on this golden opportunity. I mean, does he know how hard it is to get to the top of the organic Google results? There must be many, many ways he can make money from this good fortune - referral fees, affiliate commission, full blown partnership or franchises with US IT serving businesses. For a start, why not look at all the US businesses who appear below him in the results and contact them to see if they'd like to benefit from the traffic he's getting?
I mean, at the very least, the contact form could send the email to his 'US partner' and that partner could either pay a set fee per referral, or pay a % of the job cost.
Bouncing people away from his site seems quite short sighted!