I'm still not able to see what's the difference here. In a "no trusted special networks" world as the one painted by BeyondCorp, if the Intel Mac is not supported anymore, well, you will just not be able to login in any corporate portal because the smart BeyondCorp SSO will reject you, no matter if you are at home or in Mountain View HQ, no?
I mean, I can understand defense in depth and not wanting anyway a possible unsafe device connected to the corp network which still might expose some unwanted data (i.e. I imagine a trusted device on the corporate LAN might relax some local firewall rules to make it easier to develop? I'm just guessing, no real idea)