It certainly can't say what Biden would have called a "reasonable response" at the time, whether he would have followed through on it, etc. We actually know what Biden was saying to do in the early days of the pandemic, and Trump's earliest actions were roundly criticized by Democrats.
My theory is that if Trump had come out hard for lockdown early on, Republicans would be pro-lockdown and Democrats would be anti-lockdown. I view the partisan divide on COVID handling as...well, purely partisan.
The early CDC tests, during the period we might have been able to maintain contact tracing, were faulty. A different president wouldn't have changed that.
Republicans didn't embrace masks, but it's unlikely a Democrat president would've done a better job convincing them.
In my opinion Trump's worst fault here is that he lacks the temperament for one of the most important things we needed: fireside chats. Trump is a pretty good hype man, cheering on good times, but abysmal at the somber tough message delivery we needed.
Which implies your summary of the point is based off of one of the several misreadings out there.
The United States has structural issues, many of them features and not bugs, that make a coordinated effort to suppress a contagious virus basically impossible. Biden never made the case for what he would have done different; he didn't really have to.
That's the thing about a crisis. When your opponent is in charge during a crisis, you can always say he was incompetent, and no one can prove that you're wrong.