I notice the Beeb has lately been announcing that it's 'owned' by the licence-payers, so presumably we/they'll be asked to cough up the damages/costs if the Beeb loses the legal battle or settles out of court?
Since the waste liquid is likely still caustic, perhaps it could be neutralised by combining it with carbonic acid produced by carbon dioxide capture, thus making the whole thing more environmentally friendly.
In that case there seems to be enough material in the bracket to allow enlarging the hole by 4 or 5mm. You'd also have to elongate the bolt holes or find smaller bearings.
That would be the logical conclusion if you are sure there is no screw to undo. Could be a very tight fit if there is limescale in there, or a decayed O-ring.
Clamp the bar with mole-grips or similar, near side of the orange arm, then use a scredriver blade between the grips and the arm to lever the arm away.