My biggest worry is that taking and holding land inter-shard will become that much harder since a foothold is that much more vulnerable.
I don't even have code capable of creating lower tier minerals (Solitary ghodium included; I need it so rarely and in such small amounts I just buy it off the market)
You can make T3 minerals at RCL 7 (like I do) without having to rely on an external room at very high lab utilisation; If you work for it you can earn your T3 minerals much lower than traditionally available sans market. I feel like it'd be a step back to take that away. But I am biased in that regard.
Maybe if it where respawn/noob zone only? That'd stop the frustrating 'Get minerals and win' sort of thing that could happen; but if you have the code to handle that havn't you earned your victory?
And isn't that what safe mode is used for? Shut down the attack and make them waste (at their level) the small amount of minerals they have?