He is discussing weather or not the unvaccinated pose a risk to others

And as as argument for "no" he says that vaccinated people are not immune after 20 years (which is, depending on vaccine, wrong btw).
So yes, if you are unvaccinated you are a risk.

But whatever his statement, if your points all have holes, then your argument can be (and in several of his points is) invalid.

Most people take vaccines as children and then never again. By the time you are 20, you're immunity, if derived from the vaccine, is gone per their pamphlets.

We are talking here about one vaccine. There are a lot that have a "guaranteed" time frame of about 10 years, but others work far longer.
And others again, like the flu one, are basically yearly, even if you have stronger resistances in the next year. The reason is that the strands are changing so fast.