arcticfox is probably referring to the title conclusion "Olin College Produces Founders at Five Time the Rate of Stanford" not being the result of selection bias during the analysis phase (as implied for example in this comment https://news.ycombinator.com/item?id=15184748).
The conclusion "Olin College is more effective at turning people into founders than Stanford" is indeed a far more speculative conclusion due to self-selection.
"I specifically went to Olin because I thought it would best help me become a successful entrepreneur"
choose one