You’d have to ask them that but i guess it’s to do with being for the claimant’s benefit and not for a named drivers benefit.
Had no issues with being allowed mein as it has rox in it.. I need to ring MB soon as the dealer couldn’t put it on last month ( i got the plates from them for it though) and we was due to go euro disney in a few weeks but cancelled that now. So would of had to wait for the new v5 and rac to issue the greencard and stuff for travel outside the uk. Mb been great about it all.. just call them when i’m ready as it’s on retention. It will cost you to remove it but not to put it on.