If you are going to remove a couple of tons of the back wall of the 1700 original pub, then don't bother with replacing that section with a silly pillar. The technology exists - and has existed for some time - to span the whole gap with a series of beams to support the rubble work above without the need for a tube from which you can pole-dance, should the inclination come over you.
Despite what you say about being inconvenienced for three days a week, three hours a day, the little space created by the Victorian addition to the original core will be destroyed by the removal of the bit of remaining wall, and without putting up screens during the bulk of the time when bands are not playing, it will never be replaced.
I really do not feel as strongly about this as I might appear to, but it needs some proper discussion amongst all parties before what I believe to be a pretty drastic demolition is allowed to take place. You can't just nibble away at the original interior just because music is your prime interest.
I really think that the Board should have the mandate to decide on this, but I also think that proper consideration should be made before it does, because this work is irreversible. I put forward objections as Devil's advocate in the hope that it is discussed. I have no particular axe to grind.