I guess the only argument would be if he was struggling against Dabra, why didn't he turn Super Saiyan 2? It's inconsistent, but ultimately doesn't really matter.
Yeah, I think the answer would be that he was enraged in the Budokai, like, let's say a delayed rage catalyst to Videl getting beaten up, while his rage had already dwindled when facing Dabra. That'd be the most logical in universe implication.
It's weird because Goku specifically reinforces the CGs as what Gohan needs to remember to draw out all the anger and become the strongest... No mention of the Budokai was made. It may be because the CGs was more of a remarkable moment that can be more catching for Gohan. And also, since he was more enraged in the CGs, it's possible he was a stronger SSJ2 there due to rage, while his rage in the 25th Budokai was just capable to bring out the ssj2 ability out of him temporarily but without any additional boost that he'd favor when being as enraged as in the CGs.
I've entertained both positions, but all in all, as of now, I think Gohan was very likely a SSJ1. The story is still inconsistent either way... So the way the artwork portrayed him, without any lightning, which is incredibly consistent in the manga for SSJ2 barring some panels in which is isn't 100% consistently drawn, then I think it's likely the closer to the intention there.
Obviously a Gohan even weaker than his Cell Games self wouldn't be able to keep a fight against someone on full power Cell's level in ssj1 only... Which is why I'd say their comparison with Cell may be the only example in which a general comparison was made... More like being in the tier considering the many power ups Cell had displayed, without it necessarily matching the full extent of Cell's power. Let's say the level Cell displayed vs Goku already being a significant one for them to stack an enemy of that level on a general comparison of "about as strong as Cell"... Obviously it wouldn't make that much sense... But considering Cell wasn't just full power Cell, but also Super Perfect Cell, the latter of which Vegeta and Goku were aware of... And the comparison would also be kinda sketchy if it weren't referring to SPC either, as that's the pinnacle of Cell's strength. And were it referring to SPC, then Dabra would be close to SSJ2 CGs Gohan. Which is contradictory given that, even if teen Gohan were a SSJ2 vs him, he struggled against a Gohan stated by Vegeta to be way, way weaker than kid Gohan. So he could not be on SPC's level either, which means some liberty was already taken with the comparison either way.
So going a note down and interpreting that as a Cell that Goku fought to fit with SSJ teen Gohan being around his level isn't bad, specially since the story seems to also treat SSJ Goku and Vegeta as capable of defeating Dabra imo. Since pre Majin Vegeta had yet to reach CGs Gohan's level, he wasn't on full power Cell's level in ssj1 only. If Goku is surprised Vegeta has SSJ2, in spite of Vegeta leaving it clear he could defeat Dabra, then it'd make sense if Goku already gauged the level Vegeta displayed in SSJ as being capable of such. Vegeta also seeks confirmation that Goku has SSJ2. He states how each of them should take Dabra before he realizes Goku had SSJ2 vs Yakon... Which would also point to, his statement of each of them being able to take Dabra, remaining true whether Goku had ssj2 or not.
What bugs me though is that Vegeta stated him and Goku are already beyond teen Gohan before he confirmed Goku had ssj2 vs Yakon and when he had seen Gohan as a SSJ2 in the Budokai, which would also lead to ssj1 Vegeta and Goku being >> what he saw from SSJ2 Gohan in the Budokai... Which can't make sense if Gohan is still strong enough in ssj1 to battle an opponent ~ Cell (vs Goku) on equal terms... That'd mean ssj1 Boo saga Gohan was still at least on MSSJ CGs Goku's level, making his SSJ2 possibly considerably ahead full power perfect Cell and thus, outside of Goku and Vegeta's reach were them merely a SSJ1. That'd be the main thing that bugs me, Vegeta seeing teen Gohan as a SSJ2 and still assuming Goku would be stronger without a SSJ2 confirmation... That, I'd have no counter to.