with 30 years experience of that sector between them is:- ATCOs don't care as long as you stay in the holding pattern!
Pretty much sums it up
TBH I think the 22d MID is a limit to stop pre FMGC aircraft drifting towards the TIMBA hold.
As I mentioned in a previous post.........at LGW, if the STAR is a standard STAR it will have the 5.1 dme limit. If it is the "new" RNAV arrival it won't mention DME limits because they expect an RNAV 1 aircraft to stay within the protected area with a 1 minute hold.