That argument doensn't apply here: demand isn't currently being constrained by us being affraid of the environmental impact of datacenters.
Conversely, if it became literally free to operate, you can imagine we'd have a higher demand for data, storage, etc.
It's like how center pivot irrigation reduced the water usage rate per acre but increased demand for water usage in various areas because costs were lowered as well.
That's not the case if you're comparing with AC. You have to use energy (generating more waste heat) to pump heat up a temperature gradient.
Find a desert under the sea and drop them all there. Some place that's basically water and dirt. It's probably going to be large enough that you could dump all of humanity's data centers there for the next 100 years and still have room to spare.
Of course you could argue that the lower cost of this cooling method will create a larger demand for cheaper servers/data storage, which increases net harm, for which I have no answer.