Can Microsoft hire employees from their supplier base to become commodity managers for the same co.?

I have been a Foxconn employee to supply interconnect components to Microsoft, however and I resigned my job. Part of it was because MSFT hired a Former Foxconn employee to be my commodity manager. I was new to the account, when that Gentleman knew Foxconn inside out and was calling my factories behind my back. My manager would never send me to China to meet my counterparts there, so that I could be of better help. When I took the MSFT account, my manager gave me 3 hours to decide, was that legal? Question, can a corporation hire people from a supplier base? Especially someone who was personally involved in all of the projects and knew the inside costs as well? And then have that person play against his former company - who was a supplier?