I don't know guys -- this smells like bad fish. With the man who had his legs blown off helping to make the ID, they are probably the guys who did it, but it doesn't make sense. Okay, he is smart, lonely and sympathetic to Islamic hatred of Americans. He grew up in corrupt and violent places, and was after "career and money" - now here is where is goes off the rails:
1) They pull off a successful, very high profile bombing, in a place filled with cameras and surveillance video and witnesses, most of whom survived to tell the tale. So you go back home and continue to make more Bombs? Not get out of State? Not get out of the Country? They are almost sure to ID you, so you gotta lie low. They should be pulling a pony boy, dying their hair and hiding in an abandoned building somewhere.
2) They then see themselves ID'd on the news. Their reaction? Hey lets go rob the 7-11 at MIT? Seriously? Way to lie low guys. Were they getting "get outta dodge money" - if so, why rob an open business? With Security Cameras. With an armed security guard, who you do kill. Police definitively know where you are, and where to keep looking. It never occurred to you that you would NEED to get out of Dodge and be prepared for that eventuality? Really? But wait, we didn't get enough from the 7-11, so we stop at several more ATMs on the way out of town- DURING a police search for them?
3) So they hijack a car - one with a security tracking system, and then decide to abandon the vehicle but leave that witness alive?

Tin Foil Hat time.
I suspect that someone paid him to do it. Used his Islamic hatred and the lure of a large sum of cash to go do this hit, and maybe another - which is why they had extra explosives. Remember he grew up where such violence and contracts were commonplace.
But Something gave this kid the idea he was safe, and he therefore didn't make any plans to get out of dodge. None. Then he actually gets ID'd- and realizes he is screwed. Maybe its just sheer arrogance ( but that is arrogance to eleventy!!!)- but I think It would take a sane person at least a week to get cocky and sure they wouldn't be caught given the number of pictures and witnesses they were dealing with. I think it is more likely he was depending on the person who gave him the contract to protect and/or evacuate him if needed. That person didn't show and he panicked. If you have access to ATM money ( $800 of it by some accounts) there is no point in taking the risk of knocking over the 7-11. I really think these guys were young manipulated pasty morons. The real perpetrators needed a delivery mechanism and hired one, telling them whatever they needed to hear to get it done, and then left them to swing. Heck, for all we know they have family that were threatened if they didn't comply.
Normally you expect there to be a manifesto of some sort. Maybe that is still coming. Maybe one will be fabricated for him. I just doubt this was the idea of the two Brain Trusts in these pictures. Maybe I am wrong- maybe its just a lonely young male getting his revenge on whatever suited his fantasies. But he seemed to be having a pretty successful life, attending school, etc. And his brother was an accomplice - not impossible, but normally people don't happen go insane at the same time.