What's left to debate here?
As far as I can see, there's a meeting on Wednesday at which Unite are going to threaten to ballot if BA don't back off.
And it doesn't look like BA are going to back off.
So then Unite and/or BASSA are going to ballot or lose face.
Then they get the results.
Then they do or do not go on strike.
Then BA deal with it.
Or is this a tactic to force BASSA to the negotiation table over the other issues still outstanding?
Either way, it sounds like Unite and BASSA are backed into a corner of their own making.