Comments can be deleted in frozen contexts

If an activity that uses comments is Frozen the comments that have been created can still be deleted by users.

For example:

1. As an administrator enable the content Freezing features.
2. Create an database activity (Ensure Allow comments on entries is set to Yes)
3. Use the image bank preset
4. Add a new entry
5. Create a comment on the new entry
6. Freeze the database
7. View the entry and expand the comments

Actual result

The comments appear with a delete button, that functions to delete the comment.

Expected result

The comments appear and have no delete button present.

This also affects assignments (and presumably all plugins that use comments)