I don't think people understand the why of "critical support" here.
When people say "critical support of Assad", they are not saying "I want to live under the Assad regime" or "I agree with Assad's politics".
They are saying there is no alternative to Assad that is capable of resisting American imperialism to the same degree AND has good politics.
The prerequisite for lionization is approving of someone on the whole. In the Stalin example you must excuse Lysenkoism in some way in order to do that.