That fun "fact" claims a degree of nefarious plotting that requires at least a smidgen of evidence.
> Marriage bars provided more opportunity for those whom proponents viewed as "actually" needing employment, such as single women.
as a claimed reason for marriage bars, which is actually quite similar to "firing for the purpose of hiring younger people", though it's being spun as for people's good, not to decrease salary expenses.
But the effects were somewhat pernicious, because as usual people didn't think about second-order effects. Or in some cases first-order ones, like women delaying marriage so they would not lose their job.