Tales of the Senzu Bean : Moro VS Cell

[big_adventure]

It's because Toyotaro is a shit writer outside of original works. I'll bet money they'll be a better reason once the anime returns.

I don't think that there's a "better" reason possible. Goku was an idiot for giving a worn-out Cell a bean before he fought Gohan. No reason works, no reason matters, it was a colossal risk with basically no possible payoff.