As long as we accept that it is one way of proving you can do something that takes a long time to do. I'm not sure that's what the author was saying when he talked about the signaling of a college degree though. It's more a matter of the acceptance of the dogma of the degree, not the signal that the application can commit to long term projects.

More directly, it's fine to look at an applicant who has a college degree and say, "this person was willing to put in the time and effort to get a college degree", so long as you're willing to evaluate other long term commitments with a similar measure. For example, if I see that a developer has a Github profile containing a handful of active libraries with commit activity dating back a year or more, I'm similarly impressed.