I'm assuming that he doesn't want to make the unit much more durable at vet0 then vet3 7 man cons, but I've seen worse suggestion from axis only crowd as well.
I think the suggestion was a concept not hard numbers.
The idea being the rak is less likely to be wiped by a single shot, but no more tanky against infantry. Or even LESS tanky against infantry (since it can still retreat)
Damage reduction are tricky though, and a 50% damage reduction would more or less require double the target size to reduce offset if my math is correct (double the shots hitting to make up for them dealing half damage) And even then it only accounts for chance to hit and not rate of fire, meaning you may run into some odd things like chasing SMG troops or semi auto rifles performance being too good due to ROF and an inability to miss