I have run the R6's at most of my tack days and they're great.
The descriptions on the R6 & R7 tyres are trying to make clear that they are 'technically' a DOT tyre, while essentially being a race tyre. The tyres have things like tread-wear indicators and (probably) other features that legal road tyres must have to meet the DOT standard.
Hoosier is making it plain that they're not intended to actually be used on the road (you've seen the tread patterns?)
I think there are better options from Hoosier for road use - currently I'm contemplating the TD series
https://www.hoosiertire.com/pb40510.htm
(or Avon)
good luck with your selection
LoBelly