Was messing around with US BOs in 1v1 last night and actually had this done to me on Kholodny. He ran 2 pumas at me and 1 of em managed to limp into my base and ended the game via arty.
He hadn't used muni up to that point as far as I could see, just spammed falls to stall and try to hold any sort of map control. He transferred any fuel to muni to afford the arty.
Imo I suppose. It's a lame way to win after an opponent gets outplayed. Probably just not allow it to be used on a base as suggested and the issue is resolved