Well, that's one way to look at it, but don't you think it'd be pointed out if Gohan started training in SSJ and then regressed to base? All we have is base Gohan fending off SSJ Trunks relatively easy. Trunks also had his aura up for the exchange, so I also wonder if he was THAT weakened. Gohan stated that Trunks could surpass him in a few months iirc but he was counting with him being around to tutor Trunks during that time. When his survival was put in check he changed that to "sometime you'll beat those monsters" or "within a few years" or so. In fact, Trunks only surpassed Gohan in 3 years time. So I think he had a long bridge to close.
I think Trunks just thought that he could be of some assistance in any way. Besides, wanting to help no matter what seems to be a trend among the warriors. I could see Kid Trunks thinking like Tenshinhan later on, the latter which wanted to test his strength against the androids even if he wasn't up to the challenge. Gohan knocking him down and making him wait all this time speaks louder imo, as in, he has to develop his strength and think rationally if he wants to stand any chance.