Not sure about the trust part. Ideally, you can evaluate the change on its own.
In my experience, I immediately know whether I want to close or merge a PR within a few seconds, and the hard part is writing the response to close it such that they don't come back again with the same stuff.
(I review a lot of PRs for openpilot - https://github.com/commaai/openpilot)
If you had left it at know you want to reject a PR within a few seconds, that'd be fine.
Although with safety critical systems I'd probably want each contributor to have some experience in the field too.