It may not be something for the grand kids until completely cleaned and repaired, which, for as fast as kids grow, may not be worth the trouble. On the other hand, it might be worth a few dollars to someone who collects that sort of bike. Rod brake on that kiddy bike is pretty cool. Perhaps it would be worth the time to do some basic cleaning and put it eBay for a low starting bid and see what happens.
Cheers,
Joe