The Manzin quote isn't appropriate. The experts themselves have stated they're still investigating the virus and potential solutions. Trump wasn't suggesting they experts missed something.
It is entirely appropriate. One person died from ingesting hydroxychloroquine[1]. Perscriptions for hydroxychloroquine increased 46X. [2] It turns out that taking it killed more people than the control group. [3].
The Maryland Emergency Management Agency received over 100 calls about injecting disinfectant as a potential cure. [4]
You know, it's possible to explore highly experimental therapies for a novel disease without naming them explicitly at the presidential press briefing during a pandemic. Doing so is INCREDIBLY irresponsible, as evidenced above.
I'd be interested in having a better sense as to what would constitute an underlying or pre-existing condition. Is limited to conditions which have already weakened the immune system?