The application of TUPE is a complex area of law at the best of times and particularly so when considering the asset purchase of an insolvent company. I'm a solicitor who specialises in Employment law but I wouldn't say with any degree of confidence that the explanation I am about to give is entirely correct. Particularly so after a couple of ciders on a Friday, without any legal research or access to legal resources and nobody paying me to do that research!

The starting point is that TUPE applies to what is known as a relevant transfer. That means:
"A transfer of a business, undertaking or part of a business or undertaking where there is a transfer of an economic entity that retains its identity (a "business transfer") (regulation 3(1)(a), TUPE)."
In this instance I do not think that either TC or PR would struggle to satisfy an Employment Tribunal that TUPE would be applicable if the deal completes. While the new company would be a different legal entity to the old one the economic entity and identity would still be Plymouth Argyle Football Club. The new company would be a successor company for the purposes of TUPE.
Normally that would trigger what is known as the automatic transfer principle which means those two employees would automatically be moved to the new company on the exact same terms and conditions:
"This principle applies to all employees who were employed in the grouping immediately before the transfer, or who would have been so employed if they had not been dismissed because of the transfer or a reason connected with it which is not an ETO reason entailing changes in the workforce (regulation 4(3), TUPE)."
In this instance they have both already been dismissed and so will not transfer. It is an automatically Unfair Dismissal to dismiss someone so as to avoid them being transferred to the buyer. It seems to me that PR at least could try and run an argument which goes that he was dismissed because that would help facilitate the deal (particularly so because Brent was told in advance - was he just told or did he require?) rather than for the reasons actually given. It is less likely that TC could run that argument and rather more likely in his instance that what is known as an ETO reason might apply. The question whether dismissals by an insolvency practitioner are connected with the transfer and for an ETO reason has been debated a lot. More recent cases have tended to conclude that pre-transfer dismissals in insolvency situations where a sale is envisaged are connected with the transfer.
However the real crux of this matter is that it is not only existing employees who transfer but also "any acts or omissions of the transferor before the transfer are treated as having been done by the transferee (regulation 4(2), TUPE)."
Put simply if the sellers owed them money then the buyers would normally owe them money. This talk of how they want 'more' or that everyone else will agree so why won't they is simply a smokescreen. Those people who have transferred over are not in the same position. The others who were sacked / made redundant are. If they are owed money then Jame Brent would legally owe them that money and he knows it and they know it. I would be surprised if Chris Webb did not know it as well. No wonder TC is content to arbitrate on this and JB is not.
Furthermore I have seen it suggested that because PR and TC won't back down (why should they if they have been advised they are being stitched up?) then JB can't either because all of a sudden it would cost him £100,000+ as he would have to pay that to the rest of the '15' what they are entitled to. With respect that seems like complete bull - each former employee can negotiate their own settlement and (without being privy to the details of exactly what is proposed) I am scratching my head as to what kind of deal would require them to all sign up to the same terms.
I have also seen a lot of talk of how TC's dispute is 'only' 6k and he can afford it but why should he have to? JB could afford to pay it even more easily and, from what we know, it is more likely than not that he actually will owe it if he completes. This is about a business man trying to buy a business at the lowest possible price even if that is below what he ought to be legally paying for it. That doesn't make him a sinner by any means but it hardly makes him a saint either.