longer ron,
Getting the aircraft to RIAT this year is not about how many F-35B are flying in the USA (availability) or their current capabilities (usefulness). Again, I'm trying to politely suggest to you that it isn't the right comparison to make. I'm suggesting that the USMC putting in the same level of effort which they did for last year's [cancelled] appearance just isn't possible this year because their direction from on high is to focus entirely on IOC in Jul and nothing else.
The alternative situation - in that the USMC were unable to declare their IOC because they didn't put in place what they needed to in time, because they were providing aircraft, manpower and support to a trans-Atlantic trail for RIAT - would be a far more strategic failure than depriving a few thousand spotters the sight of the F-35B for an 8-minute display.
Personally, I would enjoy seeing an F-35B at RIAT this year but I also think that the decision to not expend effort on a month-long UK trip for 2 or 3 F-35Bs plus AAR plus maint/spt pers, thereby risking USMC IOC, is compelling and justified in the circumstances.