And again, that's not even within an country mile of being a good faith attempt at charitable interpretation, for several reasons.

You're twisting their words into some sort seemingly overnight goodbye to all software relying on third party libs. A more normal way of taking that is envisioning a more gradual progression to some future state of affairs, where to the greatest extent possible we've worked to create an ecosystem that meets our needs. An ecosystem that's build on a secure foundation of known and overseen libraries that conform to the greatest extent possible to the FOSS vision. Ideally you don't just say goodbye, you work to create ersatz replacements, which there's a rich tradition of in the FOSS world.

Your other point was even worse:

important software shouldn’t reuse code already made, they should reinvent the wheel and in the process introduce unique vulnerabilities

Somehow, you decided that putting words in their mouth about going out of their way to solve the problem only with worst-case-scenario bad software development practices (e.g. lets go ahead and create unique vulnerabilities and never re-use code) is a reasonable way of reading them, which is completely nuts. FOSS can and does re-use code, and should continue to do so to the extent possible. And like all other software, strive to avoid vulnerabilities with their usual procedures. That's not really an argument against anything specific to their suggestion so much as its an argument against developing any kind of software at any point in time - new games, new operating systems, re-implementations seeking efficiency and security, etc. These all face the same tradeoffs with efficient code usage and security. Nothing more or less than that is being talked about here.