I agree that there exists a problem with unmarked weight limits and this affects larger riders, but I think the author's proposed change will not be sufficient to increase the availability of bikes with higher limits. The author writes:

My proposed solution, which I presented recently at the National Bicycle Dealers Association annual meeting, is to add the weight limit to the geometry spec sheet for every bicycle next to the standover height and reach

Publishing a spec is (and ought to be) a minimum obligation by a manufacturer, since the consumer has no way to compute these values on their own. So I agree with that. The problem is that unlike the standover height or wheel diameter, the weight limit is artificially constrained downward by limits of mechanical modeling software or destructive testing, and artificial limits like how much product liability the lawyers are willing to permit.

If bike manufacturers have a robust regime for testing up to 136 kg, then testing beyond that would require new processes and test equipment, all of which cost money. So a manufacturer that complies with the author's proposed rule would simply publish the 136 kg and call it a day, foregoing a supposedly narrow market segment. So a frame that could have supported more weight has been marked lower than it ought to be, while fully complying with the proposed rule.

We run into the crux of the issue: economic demand for higher weight limit bikes is not perceived as being significant. So few will supply that market. Which means there's little demonstrable demand. Which keeps the supply small.

If this sounds familiar to this community, it's essentially the same problem as with micromobility from the regulatory aspect in the USA: only the automobile is viewed as "serious" transportation, so everything else is just for recreation and doesn't warrant its own infrastructure. So no separated infrastructure is built. Which keeps viable options like cycling and roller-blading from becoming popular. Which reinforces the perception as not being a "serious" mode of transportation. Repeat ad nauseum.

There are no easy answers to such structural issues, but we can take inspiration from the popularity of ebikes in the past decade: growing from a niche of motors crudly strapped to conventional bikes, ebikes nearly single-handedly transformed the perception of bikes overall, showcasing their strengths in sense urban areas like NYC for delivery vehicles: fast, nimble, cheaper than an automobile. From there, they became popular not just for existing cyclists, but new riders, some whom haven't been in the saddle since childhood. New markets opened up, and combined with a touch of enabling legislation, ebikes have taken off.

I think the author touched upon the niche that could drive higher weight limits, and that would be cargo ebikes. That space is growing as ebikes -- a bonafide transportation answer to American sprawling suburbs -- become more readily accepted, and more fairly-wealthy suburbanites take up cargo ebikes to move the whole family.

Of course, this is going to be a slow process. And it will take a while for cargo ebike prices to come down from the "luxury" range to an "affordable" figure. But I think that's the crack that will grow to break the ice.

As for whether the demand should even be met, I saw that a different comment remarked that today's bikes aren't built for larger people, since in the past, most people weren't as large. And that's factually true, but it doesn't justify not fulfilling a market in the here-and-now. Nor does it support the idea that nobody in the past was over 100 kg (220 lbs).

A quick web search shows that some NFL players in the 1930s Hall of Fame were over 100 kg. If these folks wanted to ride a bicycle with any amount of cargo, it probably would be as difficult to find a sufficient bike then or now. So the problem has always existed, but the degree to which it's a problem has changed to include more people. That should be a reason to encourage more bike varieties, not to shut down the very idea that larger bikes ought exist.

As another commenter notes, these people deserve bikes too.