I'm surprised the gallery managed to cue the closing music and the light fade after the shock from his outburst!
Given that it was a weekend teatime bulletin, I doubt that any of the senior people to whom he was referring were in the building. I'm sure that the weekend skeleton staff of close colleagues may well have agreed with his sentiments and/or supported what he was doing, and therefore were able to accommodate it.
And that keyboard tap was his way of saying 'job done!'. I was very surprised they even invited him back to Pebble Mill on the final day of broadcasting there in 2004 after this incident!
It's likely that the middle-higher management had changed again (probably numerous times) between 1997 and 2004, so the people in charge in 2004 were not the ones that Towers had blasted, and so neither they had an issue with him nor him with them.
If you want an innuendo, I'll give you one.