Light on Nostr: >software running under someone else's control doesn't and can't generally give you ...

>software running under someone else's control doesn't and can't generally give you any security whatsoever from abuses by that who controls it
But what do you mean by "control"? Who "controls" proprietary (or any) software when it runs locally?
SaaSS is clearly controlled by the service provider, unless techniques (with varying effectiveness) such as secure enclaves, https://system-transparency.org/ (which, granted, is helped by source availability), e2e signing and encryption, etc are used.