this follows the logic in cycling races that require everything on a bicycle used in a race be available to the public within a few months (but some stuff is so exotic and produced in such limited quantity it skirts the rules)
however I know exactly why this "availability" rule popped up now
Brooks just finished supplying it's prototype 4% shoes with springs to all of it's sponsored athletes (expect many PRs from Brooks runners this autumn/winter that weren't using vapors previously)
Nike is well embedded within IAAF and USATF, if not directly sponsoring voting members, they purposely sponsor people in their immediate family to maintain control (ie. how could you vote against Nike, they put food on my plate, etc)
Nike knows it's patents will slow down any competitor from producing a similar shoe to the public but cannot stop prototypes (or competitor 5%, 6% etc. improvements from semi-custom 3D printing etc)
so this is an end-run-around
just ban full-length spring plates made of any material in any shoe from any manufacturer like the original rule 143 did
https://www.iaaf.org/news/news/iaaf-council-introduces-rule-regarding-techni
http://google.com/search?q=USATF+Rule+143+wearer+any+unfair+advantage+such+as+a+spring