Finally some info from an actual TomTom employee on another forum:
Thank you for your interest in the new Rider. We've unfortunately had some logistics issues with the product and expect to start shipping in mid-June. This means you can expect to see the new Rider in the US shops at the end of June. We’re sorry for the inconvenience this is causing you.
I'm surprised a company as big as they are can't get their **** together better than that. It's a seasonal sport, and the prime shopping season (memorial day--father's day) will pass them by, even though the product was already developed.