I would think that the mere fact that they booked out of the place indicated that they had plans to live another day. I think it's a pretty good assumption that they contemplated violence of one sort or another in those days to come, if not as attacks then as a response to police trying to arrest them.
The notion that this wasn't premeditated is utterly laughable. They left their kid with the grandmother on a pretext.
In any case, we constantly see arguments made in this forum that people are innocent until proven guilty and that is certainly the case in a criminal prosecution. Every citizen is owed that standard, but not by their fellow citizens (unless the citizen is on their jury).
The media should be careful too about presuming guilt because of their power, but when someone is identified as the person who blew themself up while killing a bunch of people they are no longer the "alleged" criminal.
In this case the two were killed by police after a firefight. I'm not sure that it's been covered in the media, but presumably the police had a reason to be looking for these two and their vehicle. I seriously doubt they were stopping every car with two Middle-eastern looking people in it.
There is evidence that the two fired on police (I actually read a report that they hurled pipe bombs at them but I don't know if that's been confirmed) and once again I seriously doubt it was because after stopping these two Middle-Eastern folks the police opened fire on them; without provocation. If someone thinks otherwise, I would say the burden of proof is on them.
To me, not being on a jury, this is reasonable evidence that they were guilty. Since they were killed we know that they very definitely guilty thus backing up the reasonable nature of my assumption at the time.
There is certainly not a legal reason why you, puzzledperson or I cannot form an opinion on someone's guilt until they are proven guilty in a court of law. We might run afoul of libel and slander if we announced their guilt as a fact in a far more public way than A2K, but none of our stated opinions about these two (or the grandmother for that matter) is going to put us in jeopardy. Neither is there an ethical or moral reason why we cannot. We would display a level of stupidity or ignorance if we formed the opinion on non-existent or questionable evidence, but that's something far different from being bound not to at all.
It's interesting that this argument is almost always used by someone who is politically inclined to giver the suspect the benefit of the doubt.