The only reason I can possibly think of that would ever give cobalts an advantage over disciples is the build times....
The base build time for a disciple is 22 while for a cobalt it is 24 (these are the base build times, game speed will change them but both would be modified by the same multiplier)...
So, on a pure fleet supply basis, disciples are building at 5.5 seconds per fleet supply while cobalts are building at 4.8 seconds per fleet supply...in short, cobalts build slightly faster on a per fleet supply basis...
I can potentially see this making a difference if you were immediately Orky rushed (we are talking 2 jumps away)...that being said, the extra DPS per fleet supply that disciples have should mostly offset this...IIRC, disciples do 9 DPS (which comes out to 9/4 = 2.5 DPS per fleet supply) while cobalts do 10.5 DPS (which comes out to 10.5/5 = 2.1 DPS per fleet supply)...
If you consider both build time and DPS, you will find that on a per second basis you can "build" 9/22 = .4091 DPS/s as Advent and 10.5/24 = .4375 DPS/s as TEC...in short, TEC can "acquire" or build DPS (via LFs) slightly faster than Advent...however, the percent difference between these values is only 6.7% in favor of the cobalts....
So, there is a difference, but it is very small...in my opinion, both factions are going to be capable of defeating an Orky rush coming from 3 jumps away and both factions are going to have difficulty stopping an Orky rush that is 2 jumps away...
Note that this analysis did not consider costs...however, I think it is fair to say that the costs are comparable enough where the DPS and build times are far more relevant...
Another thing ignored was the capital ships....on one hand, the Marza clearly has more direct firepower...on the other hand, the Progenitor has a squadron of SC (which if bombers would contribute a decent amount of firepower)...because the Marza does not have a squadron while the Progenitor does, in reality both capital ships will be contributing comparable amounts of firepower (I do believe Marza still would be contributing more)...
In a true Orky rush scenario, it is unlikely the capital ship is beyond level 1....most Marza players would have picked raze planet while most Progenitor players would have picked colonize, neither of which are abilities that matter when it comes to Orky rushing...but, if we let the capital ship become level 2 (in my opinion we would then be at a stage where both factions are more than capable of having enough LFs to make this argument moot), then we can allow the Marza to have radiation bomb or incendiary shells which would result in extra DPS...
However, if we do that, then we also have to let the Prog player pick a 2nd ability as well...since that ability could very well be shield regeneration, the Advent capital ship would actually go to great lengths in protecting the disciples from a low level Orky...this is a strategy I have done myself and have been told of by very skilled players (it is by no means a new or recent strategy)...
In short, I find very little evidence to suggest that an early TEC fleet could stop an Orky with minimal (or zero) losses but that in the same situation an Advent fleet would suffer massive losses...Sagewon and Cykur's tests also support the notion that both factions are more or less equally capable in this regard....
If a test is done that shows Orky rushing from 2 jumps away can easily be stopped by TEC but not by Advent, I would be interested in seeing those replays....