If Sib hadn't made the mistake of building wire while under fire, thus removing his Sturmpios from play, I'm not sure Aimstrong could have broken out with just Conscripts. Good play from Aimstrong though.
We're agreed at least that the SU can deal with the problem, played with flanking and stalling.
Still the Kubel isn't a huge problem vs Soviets (as both T1 and T2 have units that can chase it off), it's USF who get wrecked by it.
And TBH, is the tactic that different for the USF? You can access the M20 Scoutcar via Lt, and if necessary dismount the crew with a bazooka, or skip Lt and tech to the Captain quad, who are similarly equipped. The principal thing is to spread out, capture and stall, surely?