My problem with the level of vitriol is that it doesn't leave much room for when things are truly bad - this has caused an inconvenience and lost time to him personally, but it's not like he's really suffered, like so many people do on a daily basis around the world. I'd love to see this passion directed at (for example) issues of social justice.
I think you're underestimating the importance of this bug. For the developer of a HTML5 game platform this is a huge roadblock - it can totally ruin gameplay, prevents the use of more complex controls and ultimately hinders adoption.
40 hours of time which isn't free, no less. Time which he (rightfully) expected to produce a fix to the problem in something less than two fucking years.