Me, I created it, it's with my latest script pack. It's named "Meta_Ambush, as that's what it originally was. I just never got around to renaming the file. I'm working on universal scripts at the moment, that work with any version of SFC3, modded or not.
I've just downloaded the script pack myself, and realised that I'd left in some old scripts, delete "Meta_Assimilate", and restore the original "Meta_Scan" & "Meta_DistressCall" missions. There isn't a problem with the scripts themselves apart from the fact they are debug versions, which means they will be unreliable.