IN MM, you mean. On table top?
They would legally be crippled because they no longer are able to deal at least 5 points of damage/turn. Technically. Sure you would probably have to actually excite 3 troopers to cripple the unit in the traditional manner IG but on table top? It can be argued successfully that it isn't required to kill three/four/five troopers (Depending on formation type) against a unit that no longer does
effective game damage...
that's what i meant in explanation, sir.

edited to reflect my old age: Any BA that
can do an Anti-Mech Attack still does 4 pts of damage and a critical hit roll. So no, while the unit cannot do ranged (or point blank damage),
If they can perform an Anti-Mech Attack, they are still a danger. The question then is, Can it ( because some BA units come equipped with equipment/weapon that must be dropped from the unit before it can perform other actions (example, The Longinus BA requires the SRM module to be removed before it can use JUMP Movement Points
https://www.sarna.net/wiki/Longinus )