Still faulty logic.
In Real Life™, the Colossus remains practically unstoppable. The sheer size and armoring of it resists rapid or easy disabling of turrets/weapons subsystem/engine. The only area of safety from its beams is directly aft of the engines...in the engine wash. Bad place to be, as in Real Life™ the Colossus engine wash would be considerably more powerful then an Orion's or Hecates.
Also in Real Life™ at least grant the Colossus the same abilities you would its enemies. A single BGreen is enough to knock out most subsystems on anything up to and including a destroyer. Lost engine subsystems, and inability to manuver, would render its opponents unable to seek safety from its beam fire.
The Colossus is surprisingly fast for something its size: 25 m/s, which means that in Real Life™ it can outrun any destroyer in FS, and hold even, at minimum, with most cruisers. It is also surprisingly quick to manuver (baseball bat effect, anyone?). This casts doubt on the likelyhood of being able to effectively approach from an angle it cannot engage you at.
The NTF sabotage of the Colossus' weapons knocked them out for twenty seconds. No more. The Colossus can easily weather twenty seconds of enemy fire. In Real Life™ knocking out the Colossus' weapons subsystem would not slow its rate of fire, only degrade its accuracy, and given the size and speed of the targets it would be engaging it would be difficult to miss even so.