Dude. That site I provided links directly to the source. There need not be wording anywhere else, and it doesn't have to be reflected in other R writings or sources, because the link is quoting the official rules of the RNC, supplied at the very top of the link. Here.

Note the title of that document. The Rules of the Republican Party. Not The Historical Patterns of the Republican Party, not Pressures to be Applied Through Financial Means of the Republican Party. Rules! And yes, most rules generally must be backed up by coercive measures, such as pressure applied through financial means. But the rule- as laid out by the RNC and currently still in place- is that bound delegates are bound delegates. And should they unbind, there are not only huge penalties, but explicit directions in the rule-book to ignore that inconsistency!

And remember, that quote you just posted from Slate is what happens in the case of a CONTESTED convention. Not uncontested. Contested: bound delegates vote with their bound choice first round, and then in the likely event of a second round, they may unbind. Contested.

Look man, I hope to God this is a contested convention for so many reasons. I think it'd be politics porn for everybody who's into that sort of thing (me, you, NPR, etc), it'd bloody the candidate who made it through, it'd open the window for a third-party Trump situation which would further divide the Republican vote, it'd maybe- maybe lead to some heartfelt soul-searching on the Republican side of the spectrum (just kidding). But don't let's go around telling people that even if it's uncontested, there's nothing to worry about and voting doesn't exist until the generals. It's just not true.