It is a slightly convoluted way to say, "You should pay off high interest debt." Instead of arbitrarily defining high interest as a fixed number like "Over 7%" the poster tried to index it to the 10-year Treasury rate. That way, if the interest rate situation should change suddenly, the poster's advice will still be valid.
Right now the ten-year Treasury rate is around 2.5%, so the OP would advise paying down any debt that's over 7.5%.
Looking back at the original post, the writer is trying to give a list of priorities to invest, starting with the juiciest (401k match and paying off high interest debt) and working down to the less attractive. The idea is if you don't have enough money to do ALL the things he recommends, work your way down his list to get the most bang for your buck.
If you have debt that's at 6%, the OP would advise you to max your HSA and Roth before you pay your debt off.