No, I actually understand the capabilities of the SAMs our peers are using very well. In fact, both the SA-2 and the SA-5 have very limited mobility in the modern fluid battlefield, and are frankly, obsolete to the point I'm not sure why you're bringing them up. Even large missiles like the Buk, it's important to recognise that the official engagement altitude may be 72,000 feet or something like that, but it isn't actually true over nearly any of the engagement envelope, which is a function of both cross-range from the launcher and altitude. So in fact even a Buk is marginal against a target at 45,000 feet traveling cross-range at speed; you just need to not blunder directly over the launcher. There is no MANPAD which can intercept a target at that altitude, nor particularly any missile complex smaller than the Buk.
Obviously, I don't understand why a 30mm cannon is needed against infantry. In fact, the Scorpion could just as easily carry cluster bombs to deal with infantry; carry more of them than the A-10 can carry 30mm shells, in fact!
As for stopping power against the A-10, I think the 2A38 30 mm cannon on the Tunguska has more than enough for that. It was built explicitly to deal with the development of aircraft like the A-10 which made the 23mm gun on previous Soviet SPAAGs inadequate.
So, I think you're not looking at the whole picture with missile utilization, and also not considering the impact of the fact we still use cluster munitions on the potential CAS capability of a light bomber.
A superlative heavy fighter that averaged a 4:1 air-to-air kill ratio in Vietnam?