No. It's probably intended satirically, but in practice it's a null statement since there's no grant of anything nor an exchange of value. It's equivalent to the default of "All rights reserved". This includes any fair use rights you might have, however, and any rights due to Github's ToS, so you can likely review and discuss the code, and quote from it, but if incorporated into a product or service then it's actionable; the author has the option of asserting their rights.

There's no assertion that the method is patented so you'd probably be free to also use the technique, as long as you don't reuse or incorporate the original work. If your code consequently looks like the author's then that's usually fine too, c.f. NEC v. Intel (1989), although actually relying on this precedent is a question balancing your access to legal resources vs how much the author really gives a shit.

The default is that you’re not allowed to use it. There needs to be an explicit grant of license to change that, and there’s not.