Allow users to comment but not to delete a private task

Hi All,
I’m attempting to assign a private task to a user, allowing them to only comment on it without the ability to delete or edit. I’ve noticed that when a user isn’t a collaborator of a task, they can’t delete it but can leave comments. However, once they’ve commented on the task, they’re automatically designated as a collaborator and gain the ability to delete it.
Is my understanding correct? And is there any way for me to assign a task to a user, enabling them to comment while preventing them from deleting it?
Thanks.

Where does the task live? (is it just in your My Tasks, is it in a private project, etc.) You should be able to use the project settings to make it so that collaborators only get comment access (as long as it’s not a public/shared with organization project):