I am not going that far into speculating.
I actually think JP is just completely bummed because that momentum and desire to want to play the new album to people has been stopped. It reminds me of that momentum when MP decided he wanted to take a break from the band, and JP likely felt upset as MP asked just as their wheels were turning at a good pace. The majority of the band agreed with JP, and MP had to either stay or go, the decision was his and he chose to leave.
I see this postponement as the same feeling. Only, this time, the majority of the band disagreed with JP's feelings and thoughts.
I think it's nothing more and nothing less. JP is likely still in his fresh wounds from the disappointment in the decision. So, that emotion would still be more vulnerable to being expressed, as he does sound extremely disappointed based on his tone in that interview.
I am also extremely disappointed. But am looking at bright side for me because I won't have to rush listening through the album, mainly the epic, to fully enjoy them Live.