Yup that AND he surpassed SSG Super Saiyan in a measely 4 months. an explanation SO nonsensical and with little to no basis. the only premise for it was Frieza is a insanely popular villain and they wanted him back for another appearance, AND to be a challenge for Goku. So they needed to resort to yet another illy thought out plothole
That is truye but what we have to remember is that DBZ was never meant to be big on big plot like stort lines and all that its just fighting that's all it meant to be really, I mean many hope for Super for Pan to become a super Saiyan at least that is what I hope I mean first ever female super Saiyan would be kick ass to me.
and we also need to remember Aki is 60 now that is old.
And while maybe having Cell back would make sense lets face it Gohan has become very weak as well which is sad but not sure why they made Gohan weak as I have heard a lot like fans liking Goku more or something along the lines, this is why I hope that they make Pan a super Saiyan as she would be the first canon female Saiyan.
Remember what the nostalgia critic said every story has flaws even Lord of the Rings have a few Flaws in them.