If you want to make it about the 2020 election, I would concede you have a point. Not one I agree with necessarily, but one reasonable people could agree about. But you're talking about 2016 Trump voters having responsibility for (in your opinion) his being negligent in handling the crisis 4 years later. (I remember Pres. Trump declaring a travel ban on China in February that Democrats called xenophobic and racist and crazy, and Pelosi said people should still come out and party in the streets that it was perfectly safe, and Trump was just overreacting. It wasn't till it was politically advantageous for them that Democrats started claiming the opposite, i.e. he waited too long. But that's my opinion, you have yours and you're entitled to it.)
And 'whataboutism' is a valid point when it demonstrates the hypocrisy of the original accuser. The term 'whataboutism' was invented so the hypocrite could deflect.