I assume you are talking about the wording in Sec 2: 7 (a) and (b). I don’t read it that way.
To me, the way the whole bill is written implies they really want digital AM. If the car radio only had conventional AM, it would not be compliant. It would have to be a hybrid receiver. Sec 2: 14 (b) 3 clearly shows they want digital.
I could see this as a bone thrown to the automobile manufacturers as it might ease their worries about vehicle generated RFI. The RFI would still be there, but the end consumer would not hear it. All he would notice is poor range on AM.
The exclusion against an all digital AM station receiver is weird. Maybe that is a concession to all of the analog AM stations out there, that they are being included.