I guess, it's the trend that should be stopped. Make them targetable for autofire.
They give too much AI for an AV unit. Tankbustas is the only way to counter Heavy Armour with Requisition only. They ought to be in Ork rooster. But how are you suposed to counter a wave of 7 squigs? Some clicking-fu? WOOOOOCHA!
Seriously, they are at 45 seconds cooldown, tankbustas held in 11 pop cap per unit and mostly irreplaceable as AV unit, not to say that 5 squigs can kill fullhealth Terminators squad. Most of the Ork players do the plain thing, like helding 100 pop for AI units since early phases and then building TB's only. Totally reasonable right now. Because Heavy Armour units are the only way to effectively invest pilling Energy, especially when everything is researched and built.
So, how about to season it up? I mean, if they won't have some priority targeting, like vehicles have, you could hide them behind Nobz\Boyz for the same effect. Or just sent them first to add some HP's to your melee mainliners?
It was a good try, just like PIAT's in CoH2, but should be revised.