I don't think "a bit of a stretch" quite captures the exaggeration. It is, in fact, a huge ridiculous stretch that should offend anyone who knows what slavery actually is. It's not even in the same ballpark as conscription. (I recognize, though, that you appear not to entirely buy this terminology yourself, which is admirable. The anarcho-capitalist community could use a few more people who think critically and take language seriously.)
In cases like this the government does not compel anyone to do anything. Rather, it permits them to engage in a particular line of business on the condition that it does so in a way that attempts to re-internalize what would otherwise be a host of harmful externalities.
In cases like this the government does not compel anyone to do anything. Rather, it permits them to engage in a particular line of business on the condition that it does so in a way that attempts to re-internalize what would otherwise be a host of harmful externalities.