I'm a politician first and software engineer second.. I have _never_ given anyone or any sub-organization bad feedback, directly or indirectly. I've advised someone on something that could help them be better, but I've never externalized it as grumpiness I have. It's never worth it. Smile and nod, disagree and commit, focus on whats in your control, and tend to your network. If they're not paying you for an honest ex…
Disagreeing to an exit interview seems unnecessarily hostile... and it may lead to on-the-spot ad-hoc informal exit interview anyway... and the questions may take into account the fact that you disagreed to it.
Just agree and comply, tell them what they want to hear. It's easy.