Nebulous and poorly-defined concepts
Toby, you write very eloquently and your blog is great. Having read all the posts here (and 2013 and 2012) it is clear that there is an ongoing discussion on the "rules" of ultra-racing (and in the comments on your blog). After reading all points of view posted and the written rules, it would seem that the "What would (or did) Matt/John/Craig/Ollie/Eszter/Jefe/Kurt/Jay do" is the litmus test of anything which is in a grey area.
To have a rule book cover everything would be impractical (i.e. even most government legislation fails in this task), so one must rely on the racers keeping to the spirit of the event when in doubt. The written rules are sufficiently clear to establish this spirit of the event and the TD won out over the GDMBR partially due to its intelligent take on appropriate rules.
I have not seen any evidence of a "growing number of racers" using TM as an excuse. Look at the Tour Divide movie and you'll see at least 12.50% of the finishing riders in 2008 breaking the simple, no interpretation, written rules. In the absence of evidence to the contrary, it seems that a greater percentage of racers are actually becoming more compliant with the rules than in the past.
Leading by example is usually the best way to ensure compliance with any set of rules, and when looking at all the racers (from GC winners to 30+ day battlers) in the current and past years I see consistent compliance with the spirit of the the race being "self supported".