This isn't the same scale difference as between S1 and S2.
Look at Formula 1. They keep changing the rules for car specs, the cars keep changing, they even change the shape of tracks slightly over the years, but the Records are not ignored. They don't say "well no turbos anymore, and we'll groove the tyres, so you should all be slower, but we'll give you a chance to set a new WR, so we'll ignore the old ones now."
They should be able to write a program to scan the existing hotlaps and remove all those with front suspension set dramatically higher than rear. They used to manually remove the spr's posted with wall-riding on the hotlap in S1 days.
They should leave the laps in place, then after a month review how new times compare to ones uploaded before April 21. If people aren't getting close to the old times, then remove the older laps. THAT would be fair, and an interesting comparison in the process.
To say the old WRs are invalid is crazy. People drove with the limitations of the game to set them. As WGooden says, the same people are going to reset the same WR's, unless more people get off their butts and actually post times now. Biggie will still own the RB4 hotlaps, Flotch will still own the rally ones.