Google 'helicopter speed/altitude records' for an answer.
I think you're missing the point. The question was rhetorical. I think it's pretty apparent that the aircraft in question was not a helicopter. So then the question becomes how it was identified as a helicopter. Wrong ICAO somehow keyed in to the aircraft's computer?
It was most likely just a bad packet. We probably get them all of the time.
Many times I have seen aircraft squarking 7700 on one device and not on the others.