Exactly, they're not suggesting that the general public would use this. In fact, the point is that the general public wouldn't use this.
And not “a few geeks” specifically, either, but rather those who these laws are ostensibly targetting - those exchanging CSAM or organizing terrorist operations or whatever who may or may not be geeks as a whole but probably have at least enough geeks available to help them set this up.
For many purposes they wouldn't even need any sort of public-key encryption; simple password-protected zip files with the password sent in a separate message, or perhaps by a separate channel, would be sufficient to bypass this scanning.
Likely, actually just putting the password in the message would be safe enough (I've done that in the past to get round enterprise email scanners disallowing .exe files).