2am, I guess you meant.
You would probably have put users of nearby roads, inhabitants of any neighbouring properties at risk because the motorway barriers and run-off areas have been built to deal with a 70mph off (or should have been) and not a 120mph one. If they're strengthened suitably, I've no problem with motorway speed limits that can be varied upwards, subject to the driver's eyesight being certified good enough to see the stopping distance (180m at 90mph, which is ten times the driving test eye test distance...)