It is quite amazing to see a lot of people here which have registered here as ATPL holders having such a poor knowledge on a Tower Controller responsibilities.
The list of those responsibilities and duties is very long in some airports, and can be a challenge for a single person but I can assure you that confirming in which runway aircraft are lined up before issuing a take off clearance is not of that list.
I am also 99% sure that if the controller had seen it or had a doubt he would have said something. No controller in his right mind would have done otherwise.
As to judge on the priorities ( e.g. telephone versus looking out ) you have to be on the spot to do that . It is very cheap afterwards to say you did not have your priorities in order, should have done this instead of that and it would have saved 50 lives...I have heard that argument before in court on another accident and frankly, this made me sick just to watch the controller listening to that.