In the IT / Telecomms world bonding was considered for some time, due to the high numbers of staff receiving expensive vendor training courses and then leaving to go freelance.
There was a question at the time whether this was legal acording to European employment law, however the majors got around it by creating anti-poaching agreements between each other and the vendors, thus safeguarding their 'investment'
Not being directly involved in aviation I can't comment on the rights and wrongs of FR's policy, however it would seem to mirror what's going on in other, non-aviation, related industries.