[kmfrk]

But isn't this problematic, since they would have to raise more money later on, considering that they'll be diluting their shares a lot.

Doing a $5M seed round at a $25M valuation after Google's offer is, what, a dilution of 20% total shares?

I get that they can't do an evaluation that is higher than the next one, but they must really have recented taking the offer - perhaps for reasons of working at Google for four years for the $25M bonus.