Great. That's what I needed to know – and why I think the wording actually muddies the issue unnecessarily.

Moreover, stuff like that ought to be in either the core rules or the FAQ as it's central to interpreting cards.

Astech, Willy and FireSpy are correct. It's all about the source of the ability causing the modification, and not who is physically re-rolling or changing the die face. It's why a ship with Zuckuss crew that is locked by OL can NOT modify OL's defence dice, it's why Palpatine CAN modify a friendly ship's die, even if that ship is locked by OL (unless the ship with Palp is the one locked), and it's why a ship with M9 can modify another friendly ship that it has locked that is using Snap Shot.

I couldn't find it but I did get a response from Frank some time ago confirming this.