Try it without the random capital letters and it can still be a Juggernaut, seeing as "battleship" can just a likely refer to a ship that does battle. 
I typed it verbatim.
Well not quite verbatim, it should say massive proportions. 
Now it is.
It's in the form of a subliminal message, it's hard to see but at the same time it's in plain sight.
Try looking for "GTVA Battle Ship of epic proportions."
Which was obviously an easter egg and shouldn't be taken seriously.
It is the ONLY evidence of a classification. The way I see it's simply ignorance to try to even push away the one and only existing hint of what it is.
In retail colossus is clearly meant to be the GTVA's version of the Sathanas. See: both have the same armour, the same length, and are both the species super-capship of Doom!!
TM, even if, later on the Sathanas Juggernauts outnumbered the collosus >80 to one, the Sathanas did not grow in size and power, only numbers (albeit, supernova). Also note that the colossus and sathanas have equal casualties; colly kills sath, sath kills colly. It seems to be quite implied that the Colossus is on the same level as the Sathanas, to create a far greater realisation of "we are so in for it" when >80 show up. This seems to contradict, however slightly the "ONLY evidence of classification" it being dug up from a text reference in passing during a cinematic, which in the original game, read absurd text such as "Maths is cool" (pffft!)(or is it math is cool...) and is clearly not meant to be legible.
And, obviously due to the GTVA designation, the Colossus is definitely meant to be an advanced warning and control system following the line that freespace ships follow.