MMike1969's may have stated it a little forcibly, but I also almost had to gag when Matt spewed that responsibility line which was crap coming from him. In his defense, it can be claimed that he did stay pretty much inside the boundaries he agreed to with Wade up until 9.11. After that, his judgment was crap and 9.11 was certainly a factor in that for him as well as for the rest of the crew who pretty much had trouble holding it together.....
It is only now, in the story that we see them starting to put some perspective on things and just maybe Matt's responsibility line was his recognition of what he needed to do and/ or become as a man.
As usual, Arbour has painted us a character with flaws, passions and aspirations that each of us cannot help but be somewhat entranced by their actions....