Rules and Laws are birds of a feather... because they stick together

Previously in this blog I wrote about the relationship between "rules" by horse organizations and "laws" of the state, established by the Legislature.  Critics asserted that rules regarding horse welfare would do little to deter horse abuse.  I offered the link between the standard of care as established by rules, providing a legal remedy.

I read today the growing controversy over the elimination of a Dutch dressage rider in an FEI competition because her horse was found to have blood in its mouth.  (Read the Horse and Hound presentation of the controversy here).

Image unrelated to parties involved in controversy.
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Key to the controversy is that riders were eliminated for a rule that didn't exist:  

"However, astonishingly, an investigation by continental magazine Horse International found no such rule in either the FEI's dressage, general or veterinary regulations. As a consequence, the FEI is creating a new rule covering blood in a horse's mouthBut this is of little comfort to dressage riders who have been eliminated in the past."
It is a possibility that prior-eliminated riders will pursue legal action for the damages incurred by the wrongful removal from competition.
However, FEI's position is that: 
"FEI director of dressage Trond Asmyr contends the issue is covered by rules concerning the welfare of the horse in FEI General Regulations (GRs) 141 and 142 and Article 430.7.6 of the dressage rules."
Are general welfare rules a sufficient foundation for specific welfare issues in competition?  Do they provide an adequate defense to the potential allegations of eliminated riders that they were eliminated for a non-existent rule?  What if a horse was eliminated for blood in the mouth that wasn't caused by abusive handling, but because he nicked his tongue (as was the case with the horse Parzival), are the general welfare rules then irrelevant?
In this situation, these rules don't connect to the legal standard of care, but they do create a cause of action based on the possible errant enforcement of the rules, resulting in legally recognized loss (perhaps loss of profits, loss of horse value, reputation harm in the dressage community, etc.)
Or perhaps your position  might be that anytime a horse has a hint of blood in his mouth, for whatever reason, innocent or not, he shouldn't be ridden for welfare reasons, and thus the rules are applicable to such a case.