1) That's fine, it's their job. If they own your units there, it's logical.
2) That only works en masse but you just have to move back slowly and it's fine. It's not woring anymore against half decent people, and the TOPAS isn't much help against HAT (High Armour Tanks)
3) This kinda works though, but recon and you see it coming, you spread out, and it's fine.
4) That doesn't work at all though. Not enough numbers of Zhalos/BMP 685 etc... To make a really potent force.
And overall, your post is quite irrelevant as it's just crying about infantry. Not about the TOPAS itself.
I must admit, it went slightly off track to more general apc inf diretion.
But what comes to the points above, your explanations doesn't really stand good. The problem is that for a price of a 1st line MBT you can field around 10-15 pcs of 5(10)+5 apc inf, even more, if (when) your enemy has his MBT's vetted. The math just doesn't work well at all.
Half or even full decent tactician for that matter can try and see how far he can back up his MBT before 15x enemy apc's inevitably catch up. There's no talking about destroying the numbers required in time - not even nearly - and given the current apc hyperspeed+inf instalawing+shock effect defects the cheapest law infantry acts in very many situations as the best anti-tank weapon! They are expendable, enemy doesn't gain much points by destroying them, and they are just insanely effective when rushed close-by and easily can inflict points-wise much more casualties than losses, even when the destroyed-loss ratio is horrendous.
Of course the subject is also somewhat game size relevant, and for all-open field a decent player might readily prefer some another kind of tactic.