One of the basic tenets of ACAS is confidentiality of discussions:
Although largely funded by the Department for Business Innovation & Skills (BIS), Acas is a non-departmental body, governed by an independent Council. This allows us to be independent, impartial and confidential.
By his actions, Simpson has demonstrated a breach of trust. ACAS would be well within their rights to bar him from future proceedings.
The fact that both BA and ACAS have chosen to turn a blind eye to this shameful act shows that they are trying hard to overcome the constant obstacles that this witless bunch of 70s union cretins keep trying to put in the path to settlement.
Personally, I'd have dynamited the shallow end of the gene pool a long time ago.