I've been following the original thread since around September last year, and this thread since it started. To my knowledge, prior to Juan's post, nobody in that time has identified the existence of, or the words of, the disclaimer regarding staff travel when you sign for it.
Entaxi, MPN11,
You may be right, and I couldn't easily find the quote via the search function, but I have seen it posted somewhere quite a while ago (and I'm sure I'm not becoming senile and only remembering it from the BA Staff Travel internet site!) The trouble is that this dispute has generated upwards of 15,000? posts over the last year, so trawling through them is tiresome and unwieldy with the tools provided.
I guess the only proof is someone finding a link in these threads - I can't be bothered to research it any further.
Anyway, the bottom line is that it is certainly out there now, and adds to the understanding of the arguments.