Youve lost me there and many of my colleagues I would suspect, but do consider that most airline pilots think that Aviation Law is an american film star.
Not hard to understand your original position, which was breaking the 250 Knot legal limit was OK because it was not policed. My extension was that if you break one rule which isn't policed, then why won't your mentality let you break any number of others which are not policed. Your chances of being caught are going to be slim after all, unless you have an accident or incident.
It wouldn't be rocket science for the authorities to put in a 'speed limit' detector especially with Mode S, especially if it is to catch law breakers who break a law which is ostensibly there to provide a safe environment.
The 250Kts is probably an arbitrary figure, but if you want it changed to something higher, then why not provide the safety data that shows a higher speed is Ok and then lobby ICAO (or the CAA if you only want it in the UK) for a change ??