Yes, I think quibbling over the origin of the term and attempts to coin an alternative are a useless distraction. The term emerged organically for good reasons, and doesn't have any negative connotations as far as I'm concerned. Trying to talk about "direct loading" instead is confusing and doesn't even make sense because alternative app stores like F-Droid don't count as "direct loading" under their own definition.
I think defining sideloading as "the transfer of apps from web sources that are not vendor-approved" is a good definition, because "not vendor-approved" is precisely the part I care about. The owner being able to install stuff without Google or anyone else's approval is a good and important capability for every computing device to have.
In any case, I fully agree with the substantive portions of this article. What Google is doing here is a terrible attack on consumer freedom.