I wonder if his study was simply underpowered, and there may be a real but small effect.
An underpowered study is one that doesn’t get statistically significant results for a real effect because there is not enough data collected to distinguish between a small effect and random chance.
I associate the word “straphanger” with tabloid media. They have some words that they really like. It doesn’t really even make sense for NYC Because the subway doesn’t have straps.