Yes. If that particular project has been listed for CMM/ISO and if the Quality group has assisted the project for process compliance then they are stakeholders too. They should be there for the project closure meeting if thats the case.
"The most wasted of all days is one without laughter."
-e e cummings
Regardless of the methodology, if the Project Group will be discussing anything to do with the way the project went, and lessons learned, QA should be involved. How else can you get feedback in order to improve?
Nothing learns better than experience.
"So as I struggle with this issue I am confronted with the reality that noting is perfect."
When a project is being closed, the following needs to be performed:
1. CM audit to check if the latest version of all the artifacts are present
2. Backup of all the artifacts including the project related mails
3. Customer acceptance
4. Decision on the open bugs
5. Project retrospection
6. Release of team resources
7. Collection of project metrics
If you carefully think, you can find that in each and every task mentioned above, QA has a role to perform....whether it is related to QA artifacts or QA team members or Quality metrics or retrospection etc.
And the above points are only a part of the checklist for project closure.
So, if QA is required during implementation of a project, so is QA required during opening or closing of the project.