I would be against it, really.
Antags exist purely to get action and danger on the round.
More a traitor is dangerous and prepared, more it is exciting for the whole round.
When i play security, i would rather hope to be against one syndicates overpowered with tons of advantage and weapons and give an actual challenge to security than a syndicates who got caught with a esword, got stun, processed and there, it's done.
I agree that some meta are quite obvious to see on players and make them predictable. But if we start tweaking and nerfing antags more and more, syndicates round will just end up being extended rounds really.
Yes i'm kind of overlooking since we're only speaking about mindshield here, but my point stay the same.