It depends on your definition of price gouging. You're defining price gouging as having the price reflect the marginal cost of the drug. I (and I think GP as well) would define price gouging a little more broadly and say simply that it's setting the price unreasonably high. Since marginal cost is not a reasonable pricing mechanism to achieve the desired goal, It's not a good basis for an argument that the price is reasonable and not gouging.

I think the term for what you're describing is "Supracompetitive pricing": https://en.wikipedia.org/wiki/Supracompetitive_pricing

(I'm not sure whether the evidence justifies that claim either, but the claim is a lot stronger than gouging)