There should be no need to write it off as charity. If you spin up instances, it's a cost which gets written off as any other cost. If you use those for folding at home, that's your (business') thing. (Obviously, this is generalized and your local tax situation may differ)
That’s their point. If you’re billed for instances, but those instances are used for charity and can be written off taxes, then why not? Tax write off donations in the form of product usually help clear out stock/keep things moving. They’re like a guaranteed sale. So it may be best to appeal to the providers of the instances.