If you read ICAO amendment 167 to annex 1 , specificly this part
A State may wish to impose a lower maximum age limit than that specified by ICAO in 2.1.10.1. It may do this for the licenses it issues, but, as stated above, it cannot prevent an aircraft operated by a PIC holding a licence from another State, who is below the ICAO upper limit, from operating in its airspace.
Knowing that the US is an ICAO country this would imply that ,yes foreign carriers who's pilots are over 60 can fly to the US!
http://www.icao.int/icao/en/trivia/peltrgFAQ.htm#30 Neil