and Grillo seems focused on not becoming a part of "the system" which he (justifiably imho) sees as corrupt.
But I agree with you that bit reads counterintuitive - I'm pretty sure he is NOT wanting to go to a US style of campaign funding. I think however that risk is not so big - he just wants to take away the funding that he sees as now propping up corrupt parties. Note that it is not about ELECTION funding but funding for parties as a whole that is being discussed.
Also take into account that Italy was mismanaged by Berlusconi, who controlled both his own private media concern AND the state media, and thereby the entire debate. And after being to critical of the socialist government in a joke, Grillo was banned from the state channel as a comedian.
As I said above, what the elected representatives will do is anyone's guess. They seem to typically be young, well educated and female total newcomers to politics. I've got muuuch more faith in them than in 95% of the politicians I see every day.
I think your concern is legitimate though. I am personally in favour of public funding for both parties and elections, and this position of his may be overdoing it (also notice he is saying "should they propose it, we will join" - is not the same as proposing it yourself . Having watched some interviews with him, and his public performances, it's safe to say he isn't above some grandstanding and hyperbole (as is evident in his public performances), but the ideas that underly it all (as apparent in interviews) are very sound.