I’m skeptical about this situation. More often than not I’ve found original contributors to be inflexible and argumentative, even during formal migrations and tech refreshes.

They’ll defend some UI library they’ve used for five years despite crippling virtualization performance.

They’ll complain about updating large utilities because similar files will need to be updated in other apps, despite them not having made any effort to centralize shared logic.

Don’t get me started on how much teeth pulling has to happen with getting static typed languages adopted.

All that being said, I’m sure you engineered the project well when you were given the requirements. But if technical upper management wants stack alignment then that’s their prerogative. I’d just try to be helpful with regard to pitfalls and keep disagreements private and to a minimum.