I would argue that Russia was imperialist during the tsar empire, the Soviet union and today. It just never stopped exploiting their colonies (at least everything east of the Ural are colonies inhabited by indigenous communities not recognized in their fight for freedom) and the Soviet union smashed all the attempts to create a socialist community that was beyond bolshevism like the black army in Ukraine or the anarchosyndicalists in Spain. As a leftist myself I don't see any reason to have solitary with Soviets and people who refere positively to them.

yeah, makes sense, but exactly like you said, credibility is important. being anti-imperialist in general with a focus on us imperialism is very different from being against only american imperialism while actively supporting the imperialism of other countries such as russia or china