No inference needed. Gordon Pairman & Chris Louis have both confirmed that it's once only.
Of course, in the crazy world of speedway regs this could change several times before next March.
... and as I pointed out, isn't necessarily involved in every SCB Court hearing.
Has there been an official announcement of the appointment because the SCB site still lists Gillias, Steele, Reeve, Harkess & Pairman as the membership?
They aren't. A minority of the SCB board members are made up from a tiny minority of BSPA members. Anyone appearing at an SCB hearing has the right to object to a member of the SCB Court which could, in some cases, sit without any BSPA representation involved.
If you mean about only 1 use per meeting, Chris Louis says the following in his AGM round up; "It has been replaced by an old fashioned tactical substitution where you can replace a rider with one that is in better form or whatever and you can do that once between heats five and 14 excluding heat eight."
I thought people wanted less doubling up, not more. It's a long-standing rule that was removed for just 1 season which opened the flood gates to a situation which supposedly has put a lot of people off the sport. Nicholls had his chance and didn't take it.
It's not complicated. Until last year he couldn't, this year he could have done and next year he won't be able to. This year was a case of fixing something that wasn't broken, as they're wont to do, in fact it made it worse by allowing more Premiership riders to double up in the Championship.
Gordon Pairman has already answered the question, it's once only.
http://www.speedway-forum.co.uk/forums/index.php?showtopic=85633&view=findpost&p=3058705