I mean it makes sense. We already know Forsythia is safe-ish to eat, has antiviral properties, and it's probably growing within a couple blocks of wherever you live. If it works for COVID-19 then that's kind of the ideal scenario. ~80% of people recover on their own, so a treatment doesn't even need to work that well if it's something that's safe enough for people to just start taking as soon as they get symptoms but before they're sick enough to warrant seeing a doctor, if at that point it can actually make a difference in clinical outcomes.

Something that slows down viral growth by 10% isn't going to do anything if you start taking it a week after you get sick, but if you start taking it at t=0 it could make an enormous difference.