Amazing. Welcome back to the world of selective rule book reading

It's the Steadfast argument (will be FAQ'd), Ironblasters can stand and shoot (has been FAQ'd), and Untyped spells can be cast into combat (needs to be FAQ'd cuz WoC generals can be fools) nonsence all over again.
Redflag and gang are cherry picking one rule (pg 71) and ignoring the rest (pg 58). Though amazingly if you apply ALL the rules you get this:
Chariot Impact hits the Regiment (+1 CR and Impact hits).
Detachment counter-charges (+1 CR and maybe flank +1CR and takes no Impact hits)
Because see nothing happens here to change the reality that the Chariot (or Mournfangs or Ogre Bulls) actually Charged and the unit it Charged get's impacted. Now apply the rule on page 71 to the Detachment counter charging and you get negated impact hits on the Detachment.
So simple even an Orc Elector Count should figure it out

. (Of course, that's assuming he wants to, methinks not.)
Noght