Hello,
There are various technical reasons why it isn't supported which have to do with the functionality of teaming, failover, databases and more. I don't know for certain if it was ever supported with teaming, but in 5.5.3 it was also unsupported with following note:
"Although GMS 5.5.3 can interact with MSM7xx Controller teams, GMS does not officially support MSM7xx Controller teams."
It's unfortunate, but if it was easily possible to implement properly it would have been done long ago. The workaround would be to use GMS 5.5.x, but don't expect it to work properly, and you should consider Teaming and GMS mutually exlusive (at least for now) when designing a wireless networking solution with MSM7xx Controllers.