A lot of people have a purist attitude to politics. "Critical support" is a vital part in understanding these positions of Hexbear and others, that one can support a side of a conflict and still be critical of it. Geo-politics isn't a simple binary. No two groups will perfectly align, but that doesn't mean they can't see mutual lines of benefit despite their disagreement. For example, just because someone supports Ukraine doesn't mean they have to defend everything their government does, such as supporting the neo-Nazi Azov Battalion. It would be absurd to assert that! Similarly, it would be absurd to tell the communists still crying about 1989 that they support the entirety of the capitalist Russian Federation, the same RF that destroyed many of the gains the USSR made for both countries by enabling oligarchs to loot the place and plummet life expectancy.

Well can Eastern Ukraine?

Because as a "sovereign" nation, Ukraine is an amalgation nation of two bordering existing countries of which the partner organisation NATO's sole existence in question is to be enemies with one of the two bordering countries and thus used deadly violence to suppress any dissent from its Eastern half.

This is in stark contrast to the US full-scale invasion of Iraq and Afghanistan, and further invasions of Libya, Syria and Palestine which WERE sovereign nations, where no such dilemma took place.
Bush' full scale invasion of Iraq was based on lies.
Bush' full scale Afghanistan invasion was based on searching a fugutive.
The full scale bombardment of Lybia was because the US did not like Lybia's leader.
Same with Syria.
For Palestine, it's Israel that wants to genocide the country.