The edit is being described as telling them to add a 59 to 92228, not a 25. 92228 is not an E&M, it's in the medicine section. If you run it through another edit checker such as Optum, etc. it suggests the same thing, to append a 59 to the 92228 (provided documentation supports).
I agree with the OP, it doesn't make sense to append a 59 to 92228 in this scenario, it would seem modifier 25 should be appended to the E&M like you state. If you read the definition of modifier 59 it specifically states, "To report a separate and distinct E/M service with a non E/M service performed on the same date, see modifier 25." This should be all you need to explain to NG.
The only thing is, there were no other procedures being reported on the same date for this particular edit you see, correct? The 92228 wasn't bumping up against something else when you ran the edits?
If it's a new update they just did, you may want to check with the NG team. Also, did you make sure they are NG edits and not custom practice ones?
Unless there is some specific guidance from the payer or it's only firing for a certain payer, it doesn't seem correct. It seems odd to me that Optum and other edit checkers say to do this too though.