I personally disagree, since it is obvious that this did not happen in the normal anime time-line we have no way of knowing whether or not the ROSAT was even used in this time-line. On the whole Gohan's wearing a Piccolo outfit, when Gohan wore it for the Cell games it had nothing to do with anything that happened in the ROSAT (if anything the training in the ROSAT would have made him less likely to wear the Pic outfit since he had just spent a year "bonding" with his father), it was due to the training that they had together in the Saiya-jin Saga, so the fact that Gohan was wearing only means that in this time-line he did have some sort of bond with Piccolo, not that he had been in the ROSAT.
We have no other way of debating on how powerful they are without the timeline, though. Anyone could just spout off anything without a base, and from what we see in the movie, there are things that show they're post rosat. I also think you missed my point about the uniform. Everytime we've seen Gohan, from when he first transformed, until he exited the rosat, he sported Saiyan armor. Once when Gohan exited the rosat, he received Piccolo's uniform, and that's about it.
Gohan also transformed into a SSJ in the rosat, and nowhere else. There could be other scenarios, but I'm going by what we see in the movie and the comparisons.
Vegeta was not an USSj in DBZ movie 8, and the fact that Broly defeated Vegeta faster than he defeated Piccolo could be due to the fact that Vegeta attacked Broly later in the fight than Piccolo and Broly's power kept getting stronger towards the end of the fight. It could also be due to the fact that since Vegeta was the Prince of the Saiya-jins and Broly obviously had something against Vegeta for that, Broly fought a little bit harder against Vegeta than against Piccolo. Granted none of this is 100% positive, Piccolo could have been stronger than Vegeta in DBZ movie 8, but there is also evidence that presents us with excuses for why Piccolo lasted longer.
Actually, Vegeta was a USSJ. Take a good look at Vegeta when he dashes to Broly to take him in; he has all of the characteristic of a USSJ, and he was never that bulky as a basic SSJ. Trunks also has long hair, which we only see when he exits the rosat too. Vegeta being the prince doesn't even matter, because Broly squeezes his face for a couple seconds, then he's finished. If he really wanted to pummel him, it would've been far worse then that.
And also, there is no evidence (to my knowledge) in DBZ movie 8 that says that any of the Z Senshi have been in the ROSAT.
There's a whole lot.
I just use the simple answer for this one: Gohan didn't have the electric bolts around him so (IMO) he wasn't a SSj2. Once again there is no evidence or reason to believe that Gohan had been in the ROSAT during the DBZ movie 10 time-line, especially since you can assume that DBZ movies 8 and 10 take place in the same time-line. There's also the fact that Gohan sees Goten go SSj in movie 10 and yet he is surprised to see Goten go SSj later in the anime (and several other reasons) proves that this movies takes place in a different time-line. All in all, we know that the movie take place in different times/universes so using details from the manga to explain anything in them is very sketchy.
When Gohan see's Goten go SSJ, it's during the beam struggle, which means, Gohan's reaction to Goten becoming SSJ just wouldn't matter at that point if he never saw it; or, he did see him use SSJ before.
As I said before: I, or anyone, could just say that Broly is around Android #16 or Imperfect Cell if we just go by the alternate timeline argument. It makes more sense, and is far better to use information from canon timeline and make comparisons.
Heck, I could say Goku was the only one who went to namek when Cooler arrives, and that Gohan & Krillin was on earth the entire time, since we have nothin that shows they did. That wouldn't make the least bit of sense, though.
"First I whip it out! Then I thrust it! With great force! Every angle...! It penetrates! Until...! With great strength...! I... ram it in! In the end... We are all satisfied... And you are set free...!" ~Dante~