If the author is using the free plan, Github's 'plans and pricing' indicates that's for 'open source' projects.
As far as I can tell, there's no way to turn off a 'public' Github project's download, fork, and pull request functionality. Indeed, those functions are emblematic of the service, and they're meaningless without grants to make copies and republish derivatives far beyond the legacy all-rights-reserved defaults of legislative copyright law.
IANAL, but placing code on Github, where those features are mandatory and expected, looks like an overt act authorizing related copying and modification — an 'implied license' — even without the explicit grants provided by a formally-expressed open source license.
You are definitely wrong in your 'definitely' assurance.
Someone absolutely can get implied permission, from either a physical property-holder or IP rightsholder, when the owner's actions (or even non-actions) are reasonably interpreted to have indicated mutual assent. or created a 'constructive agreement'. or simply waived some rights (modifying the 'all rights reserved'). Some examples of relevant legal principles:
It gets murkier in copyright law, because legislation has often been crafted to supercede common law and court precedents.
But these are still potent issues; for example, Google's lawyers sought a summary judgement against Oracle on many of these 'equitable' grounds, based on Oracle's public statements and actions.
Also, the idea of an 'implied license' was a central defense used by those sued by copyright troll Righthaven. (The Righthaven entity has now lost cases right and left, and is facing sanctions for its legal misconduct: http://righthavenlawsuits.com/.)
So it's not just that Bill Budge won't sue. It's that if he did, and asserted that his intent was always 'all rights reserved', he'd almost certainly lose. Defendants would have a strong, perhaps ironclad argument that upload to Github was implied permission for lots of copying/reuse/modification. (That is, you can't put something into a world-readable folder that by custom means "download, share and improve me" – and then assert that's not what you wanted people to do.) And that goes doubly if Budge is on the free plan, that's reserved for 'open source' projects.
When informing people about the letter of copyright law, and the maximal interpretation often asserted by rightsholders and literalists/authoritarians, it's important to also communicate how copyright law is really practiced and interpreted by the courts, and reasonable people. Many of our era's emblematic companies and services -- including Github, Google, YouTube, and blogging -- absolutely depend on the more liberal, fuzzy, implied-permissions and reasonable-balances practice of copyright law.
As far as I can tell, there's no way to turn off a 'public' Github project's download, fork, and pull request functionality. Indeed, those functions are emblematic of the service, and they're meaningless without grants to make copies and republish derivatives far beyond the legacy all-rights-reserved defaults of legislative copyright law.
IANAL, but placing code on Github, where those features are mandatory and expected, looks like an overt act authorizing related copying and modification — an 'implied license' — even without the explicit grants provided by a formally-expressed open source license.