Corporation tax isn’t a cost of doing business, it’s calculated after costs have been removed from revenue.
I think the point being made is that prices have to be adjusted to allow revenue to cover taxes along with other costs.
Heinlein had a scene in Beyond This Horizon (IIRC) where someone is explaining that profits are also an expense that have to be accounted for to the bewilderment of the other character who was insisting that profits are what's left over that you keep after expenses are deducted from revenue.
It's more complicated than that of course. For one thing supply and demand are usually elastic to some degree, substitutions can sometimes be made, concentrations of supply and/or demand can provide efficiencies of scale (which then results in rent-seeking) and technology is always throwing monkey wrenches into the gears to shake things up ala Christensen.
Anyway, that taxes are an expense for the individual economic entity such as a company isn't really debatable unless you want to make some sort of existential argument for arguments sake.
Profits always cover corporation tax because corporation tax is a fraction of profit (of course it's more complicated than that in reality). But the essential point is if corporation tax is lower then there is more money to distribute to shareholders, if the tax is higher then there is less.
The profits of the company are only relevant to investors, not consumers.
What the corporate income tax may do is encourage the company to defer its profits overseas and wait for tax holidays or tax cuts. It may also discourage investors from investing in your country. Those are pretty huge downsides but they have nothing to do with product pricing.