Yeah, there's an option to not allow pane tagging.
I thought there was as well, but when I went looking I couldn't find it.
There have been only a few, but important, changes to Pane tagging in MC24 and MC25. Maybe one of them changed the behaviour. Maybe this is deliberate.
Currently selecting any files/Album etc. in a Pane View enables display of the available fields for tagging. The tags that can be edited are greyed out though, so that you don't accidentally tag a bunch of files. Clicking on a greyed out tag results in a message dialogue box asking for confirmation that you want to tag the selected items, or quite tagging. Pressing F4 also enables/disables editing in the Pane View.
There appears to be no way to simply disable the display of the checkbox next to tags, when a file/Album is selected.
EDIT: Once again I have been beaten to the punch while typing. Brian has confirmed what I thought.