Clearly the Chinese are responsible for a huge chunk of the death toll. If we say of the 100,000 deaths China is to blame for 55,000 (based this on the figure for German deaths even though Germany has a much bigger population) then butcher Boris is responsible for 45,000 deaths, roughly the same as died in the Blitz. These are appalling numbers.
The thing is what can we do about China? Their economy is bigger than ours and too important internationally to hit with sanctions and as a nuclear power with 1.3 billion people we can't take them on militarily. All we can do is do the best to protect ourselves when they let loose a virus on the world.
On the other hand, we live in a democracy and can criticise and vote out our leaders. This is why a lot of people are a lot keener to blame Johnson rather than China. You can only do anything about what you control.