In my untrained eyes (from an edipemological point of view), it depends on many things. It's a slippery slope anyway ... But I sort of view it from a "practical ethics" point of view if you will ....
First thing I noticed is these result actually select people who had the antiviral administered to them within 3 days of the symptoms appearing. I have personally known people who unfortunately died in a week tops after contracting the virus (they had pre-existing conditions, namely hypertension and diabetes).
Which brings me to my next point: Suppose the antiviral exists and is viable to even beyond 85%. How much will it cost ? I'm not a US citizen, but I'm thinking insurances will rush to trying not to cover anyone who's not vaccinated or some shady shit because they always do. And how about 3rd world countries like the one I come from. We can't even get RNA vaccines, let alone an experimental drug like this.
And now my final and target point: Suppose you don't want to get the vaccine and you can afford the drug. We do have proof that even if the vaccine doesn't protect you from the virus completely, even in the unfortunate case where you do contract it, you'll end up infecting less people. Now if you choose to not get vaccinated, then you really do risk potentially contaminating more people that will either have no access to the antiviral within a reasonable effective timeframe(and that maybe not vaccinated either) or just plain infecting more people overall.
Not the cleanest reasoning, and not a mathematical proof by any means, but I believe it's one of those "mathematical" problems where the proof is finding an edge case (sorry studied in french, really don't know how they say it in english).