Right, sorted. I just hate playing a component-unlock-exploding-selecting-pointy-clickey monkey doing busy work. I prefer to let that happen to other people.

PCB Filter:
InComponent('*') AND IsTrack AND (OnLayer('Top Overlay') OR OnLayer('Bottom Overlay')) AND ((X1 < 0.0) OR (X2 < 0.0) OR (Y1 < 0.0) OR (Y2 < 0.0) OR (X1 > 50.0) OR (X2 > 50.0) OR (Y1 > 50.0) OR (Y2 > 50.0))PCB Inspector:
[ x ] Keepout ... Width: 0mmResult: see attached. No need to unlock components and select & edit, and it works for multiple offending components in one single action. The reason for setting width to 0
and enabling Keepout? Setting line width to 0 serves as a visual cue that makes it easy to spot this line is handled differently. And the keepout makes sure it doesn't show up on the gerbers. You can also do either 0 width OR Keepout and get workable gerbers. But this combo both keeps the lines out of the gerber while still making it easy to keep track of the design
intent.
Still room for improvement ... main refinement would be a better query for selection. It's a bit verbose because I currently don't know a cleaner query syntax to check for ranges. And possibly an
InLayerClass or something.

It'll get tweaked as I go along and learn more about this Altium thingy, but this'll do for now.