Yes, that’s right. Other possible effect of mutations in the spike protein can be, for example, disruption of the conformational change needed for ACE2 binding

Yes, that’s right. Other possible effect of mutations in the spike protein can be, for example, disruption of the conformational change needed for ACE2 binding (the ‘down to up flip’ mentioned in the article). In fact, such a mutation is present in the spike protein expressed by mRNA vaccines.