When you comment out those lines, create a separate user printer profile (e.g., X2D PETG/PLA) and use that profile only when slicing PETG prints. The default profile should remain unchanged, as it can’t really be modified.
What you’re doing is essentially creating a custom user profile tailored for that type of printing. Just make sure to select this profile when slicing PETG, because the slicer will revert to the default profile when you reopen the project.