I dont think Toadstool is really talking about metagame. And it's clear why calling here is fine (the better option here I think, because P4's seems in the tone that gameflow dictated his opponent would not think p4's would threebet light here).

It strengthens our cold calling range on a lot of flop boards. AQx, KQx, QJx, KJx, AKx, etc. Boards where our range is so weak that no flop raise would get any credit. Like Toad said, you may be able to get more value from his range cold calling than raising. Its an obvious postflop concept but should be applied to preflop as well.

My 2 cents.