The stats that he quotes don't strongly support his conclusions, particularly the "being infirm causes crashes" part. Saying that fatalities for riders over 55 years old have risen by more than 30% is not useful information without also knowing whether the number of riders over 55 also rose or fell in the same time frame. If the total number of riders over 55 rose by 30% in the same time frame, then it's completely unremarkable that there would also be an equivalent increase in the total number of crashes. More riders in a group = more crashes in that group, on average. The full stats might actually support his claim, but they aren't listed and he doesn't cite sources for them, so this is a pretty low quality article.
His comparisons of US versus EU stats don't support the notion that older riders are over-represented in crashes, because they don't include age-based data at all. Yes, motorcycle fatalities are much higher in the US (58 per 100,000) than in the EU (somewhere between 7 to 11 per 100,000), but automobile fatalities are also higher in the US (15 per 100,000) than in the EU (5 per 100,000), but there's no associated age data, so the best that you can say with those numbers is that people are more likely to die in traffic accidents of any kind in the US versus in the EU. There are hints elsewhere in the article that suggest the problem is rooted in something other than age: training, skill and/or alcohol consumption, but there's not enough to even draw those conclusions based on the info he presents.