You'd have thought that with only 3 engines, i.e. only 1 engine operative on the starboard side, there was an unacceptable risk of unsymmetrical thrust if the remaining starboard engine should have a problem on take-off (and the chances of a problem with any given engine are not improbable).
Does this tell us then that a B1 can easily cope with only two engines on take off at a certain TOW, and furthermore it doesn't even matter if they are both at the same side?
I suppose you could argue that the Air France Concorde ended up with pretty much only two engines at full power on the same side, and may have survived if the TOW had been less (i.e. not fully loaded fuel & Pax) & they'd got the gear up (may have some of these facts slighty wrong from memory, but you get the line of thought).