It isn't; the reactionary comment is a more general one about the relationship between self-labeled libertarians and political positions that are disguisable within the libertarian framework.
Being anti-postage and anti-national ID for disenfranchisement purposes are good examples of this; reactionary groups encourage normalizing these views under the auspices of libertarianism.
"Worse politics" is in that context; wealthy people have a (correctly!) estimated interest in lots of political positions that less monied people find unpalatable (cf. voter suppression, maintaining systems of wealth and power that stem from racism). (Right-)libertarianism provides a ideological veneer for these positions.
Poor people (including, disproportionately, minorities) are more likely to depend on public services! They're also more likely to be hired by public agencies and receive good salaries and job protections[1]. They're less likely to live in areas that private companies are financially incentivized to service regularly; they're more likely to not be at home for deliveries or not have a workplace that allows them to accept deliveries. A public system doesn't plug all of these holes, but it goes a long way.
[1]: https://www.pewresearch.org/fact-tank/2020/05/14/the-state-o...
Purposefully making public agencies inefficient in order to ensure "good salaries and job protections" for workers is a bad idea. It's highly not-transparent, and it's impossible to figure out how much the public is paying for those "good jobs." And also, you end up getting crappy service as a result. (Public transit agencies in the US are great at providing jobs with "good salaries and job protections." They're bad at providing transit. Meanwhile, in countries like Sweden, there is a lot of privatization in the rail and transit industry. Stockholm's subway, for example, is operated by Hong Kong's subway company. Denmark has bus and train lines operated by Deutsche Bahn. Europe is far ahead of the United States now in public-sector privatization.)
I have one objection to this, and one question. The objection is that, on average, the European countries listed are substantially smaller and more densely populated than the population that the USPS serves by mandate. It's not clear to me that a private company could provide uniform service without (righteously) demanding either obscene subsidies or a change to their service mandates. Neither of these outcomes are particularly desirable.
The question (or questions): given that the US already has private competitors to the USPS, what would you expect the privatization of the USPS to look like? I'm not a constitutional lawyer, but I don't think "pay a company to do it" is a canonical interpretation of the Postal Clause. In the context of private delegation, who is doing the delegation? State governments, or the federal one? Subsidies by either feel strictly less scrutable than public budgets.
> Purposefully making public agencies inefficient in order to ensure "good salaries and job protections" for workers is a bad idea.
It's also nobody's idea! The good salaries are a natural consequence of the USPS's coverage and delivery mandates, both of which are desirable (I don't want to wait an extra day for my priority mail because a private company doesn't want to pay overtime). The job protections are standard for any civil service job, and are essential for a nonpartisan and patronage-free workforce.
Furthermore, I just don't buy into the (tacit) argument that the USPS's "efficiency" should be measured with the same metrics used by a business. I expect more from the USPS than I do from a profitable and efficient business because I pay for it with my taxes, and I'd like to keep it that way.
So goes it for public transportation: I'll take my 24/7 $2.75 subway ride over the Stockholm (or Tokyo) metro's limited hours and fare zones.
The important thing is that there's hardly any of a dozen privatized large sectors that have actually improved at all, there are however multiple examples how things have become worse, with increased consumer prices and worse coverage in unprofitable areas of the country.
And what is "worse politics" but a begging of the question? Ok, privatizing the Post Office is worse than keeping it public; I agree. The question is why they believe that.