This whole situation reminds me of a situation I was in with my former band. We had a slight burst of popularity on Myspace in 2008-2009, but like most teenage bands, we fell apart before we had any momentum going.
I remained friends with the guitarist of another much more popular band that played in my hometown like a year and a half after we had broken up. He offered us the opening spot (in front of thousands of people) of their concert, so even though we hadn't so much as practiced together in 18 months, we couldn't pass on the opportunity. So we did one rehearsal gig then went out and gave it our best shot. We probably sounded awful, but the experience was amazing. It was also cool to visit a part of my life I thought I had left behind one last time.
Soleus injuries are BRUTAL. It sounds like Barnicle couldn't be running professionally now even if he wanted to. He pushed his body as far as it could go, and now he's moved on in life. But he had the chance to take the big stage one last time, and he took it. I can't say I blame him.