hello,
This is definitely not my area of expertise, but I would say that the PLMN is defined as “Not allowed” in the SIM, yes if the SIM eventually tries to access that PLMN, the HLR accepts it.
Strong chances are that I’m wrong though… IMO, the best option is to read the 3GPP, and check what it means when a PLMN is “not allowed” in a SIM. Can a SIM still attempts an IMSI ATTACH towards this particular PLMN ?
Regards,
Pix