Earlier quoted context omitted.
Yes, but unfortunately no rich person actually paid those rates: "despite these high marginal rates, the top 1 percent of taxpayers in the 1950s only paid about 42 percent of their income in taxes. As a result, the tax burden on high-income households today is only slightly lower than what these households faced in the 1950s." https://taxfoundation.org/taxes-on-the-rich-1950s-not-high/
Your 42% is overall, right? The 90% was a marginal rate, the first bullet point at your URL.
So, the top 1% of the top 1% of high-income earners, found a way for their income that would fall into the top tax bracket, to not be income. They turned it into capital gains or something else. To not do so would be crazy, so literally no one let a significant amount of their income fall into the top tax bracket, in the 1950s.