The “right of way” arguments always show up. Some people’s ideas on what this constitutes are amazing. You get this sort of attitude on the roads every day.
On a roundabout, for example, many people latch on to the give way to the right guideline. That’s fine and generally works, but at some point the person making a manoeuvre then gains priority. Like when there’s somebody at every entrance and everyone looks at each other before one person decides to move. They have priority at that point, even though there’s somebody to their right. It’s just common sense, but some people approach at higher speeds and try and bully their way through.
The OP’s scenario is the same. The driver has clearly approached properly, indicated and been patient without blocking the bike lane. They’ve then slowly moved across when safe to do so. At that point, they have priority, and the cyclist should give way to them. In this instance the rider appears to have had plenty of time to make various decisions on how to approach the driver. He may, or may not, be travelling within the speed limit but he’s clearly not travelling at a safe speed for the traffic shown.
Blame or not though, sometimes these accidents can be well and truly avoided. People are just stubborn, whether driver or rider, or both.