The JPO initiated it and managed it through the approval process.

There were lots of guys out there flying these 200-class engines and I'm sure nobody realized that they were over the 45 lb thrust limit. It didn't seem reasonable to try and get everyone to turn their engines down, and it didn't seem necessary to do so for the sake of safety either (a 55 lb airplane is more likely safer with 50 lbs of thrust than with 45 lbs of thrust - its definitely more reliable), so we initiated the change.

If you are in the LTMA program, you will notice that there is a corresponding change in the thrust limits there from a blanket 75 lbs (LTMA-1) and 90 lbs (LTMA-2) to aircraft wet weight + 5 lbs or 75 lbs (or 90 lbs), whichever was less. That was done to make those thrust limits more reasonable, because a 56 lb aircraft with a 75 lbs thrust engine isn't a good idea...

Bob