So what exactly is the problem, here? That they didn’t take a vote? Or that they’ve now taken a vote and supported you? Or something else?
Here’s the thing, in all likelihood the wall is common property and you can’t do work on common property or change the outward appearance of your lot without strata permission, probably in the form of a by-law. I know that seems heavy-handed, but it’s the law so you are going to be on the losing side if you fight it.
See if you can find a compromise – maybe paint the pipe the same colour as the wall – and everyone can go back into their boxes.
However, the chairman was a bit sneaky in not including you in the email corresponcence so you could always put a motion up for the next committee meeting that that chair be vacated and a new member be elected as chairperson.