I have had bad experiences with bubble algae I have been working to kill it off for three years and started a new reef in an effort to move past it.
Vibrant is the only thing I have not tried. I have tried all other possible biological and recommended algae eaters. Lowering my nutrients seemed to help, but did not end the problem.
There is a lot of conjecture about how to remove it and when to do it. In my experience the best thing to do is remove the piece and scrape the stuff off of it. Get a dental tool made for scraping or some other kind of pick like chisel or scraping metal thing (your dental hygienist probably has a broken one they would just give you) and physically remove all of it you can.
When it is done, get some tank water and mix it 4 parts tank water to one part Hydrogen peroxide (the 3% kind you get at the grocery store). Dip it for at least 5 minutes. I have had just the peroxide dip kill the bubbles without scraping them off. I have never had the dip kill one of my corals. I have dipped hammers and Candy canes but wouldn't do it again. It really stressed them out.
If you cant remove the coral, then just scrape off what you can in place. There are times that I have turned off all the pumps and shot peroxide into the effected area and let it bubble for a while. I cant remember how well it worked but it was better than not doing anything.
In my system with my with my ponapi and all of my birds nests, bubble algae would get in some place and slowly kill the coral as it grew and took over. I can't say that the bubble algae puts out specific toxins that pocillipora respond badly to, but my largest bubble algae outbreak was directly related to my largest pocillipora loss. When I scraped off all the bubbles in they system and removed them in a filter sock, my pocillipora quit dying.
I would not hesitate to frag a couple nice chunks off of that piece and just throw the rest away. There is more than one strain of bubble algae and people have several different experiences with it. My experiences were not good in any way. I would do what I needed to do to get it out of my system.