I think the one problem here and I'm sure HMX will openly admit it in due time is that it was a mistake to make the change during the christmas period without people available to deal with the issues it has caused.
For me, i'm indifferent to the change as topping leaderboards in this game is not something i strive for. I play for Score Wars and RB World Challenges.... or a little thing called fun.
My personal opinion is if it's possible they should eliminate scores on the leaderboard achieved with the offending combos. Yeah it will piss the people who were using that tactic off, but if they are good enough they can achieve a top score again. Other solution wipe them all. You can't nerf then have scores unachievable - however going back to what it was shouldn't be an option either.
HMX would know how many people this has affected. If 40% of people or more were using this method i doubt they would have nerfed it.