You are 100% wrong. Changes to the EPA rules on power plants does add uncertainty to the cost of electricity. The cost of electricity does impact investments by all consumers and large companies.
They might be referring to this, generally, but it's unclear from these minimal excerpts from Apple's comment letter. Presumably they have a more detailed case to make for how abandoning the clean power plan will disrupt their own investments in renewable energy.
Anyway, Pruitt is probably on his way out. Trump will presumably find someone even more hostile to the environment to run the EPA.