There's a logic in what you've expressed, but the chance of that happening is nigh improbable. I mean, if Xi was somehow poisoned successfully and the blame will certainly be automatically blamed on the Americans, by then, any semblance of diplomatic overtures and conversation is automatically dead on the water and it's not inconceivable that a quid pro quo will be enacted, or worst war.Are you saying it's not even plausible? Off the top of my head I can think of many ways to make Xi sick, and it wouldn't kick in until he left the US or even a week later. Just a quick example. Food laced with Apixaban and plavix causing a GI or hemorrhagic stroke. Easier than you think. Undetectable after a few days. I work in medial overdose and toxicology. What are your credentials?
I mean the US allowed their company to sell HIV laced hemophilia drug to HK in the 80s causing a spike in HIV cases in China. It's true, google it if you don't believe me. I would not put it past the US to try and poison people they deem to be key in another countries stability.
Are you one of those people who also think that Canada would never kidnap Meng Wanzhou? Or the US would never dare to bomb the Chinese embassy in Belgrade?
Every possibility needs it be considered and properly vetted. It's a war. So get off your high horse and consider all the possibilities.
Besides, if the CIA couldn't even manage to kill Fidel or Mao back when China was piss poor, what's the likelihood of the Americans succeeding without any trail this time against the current iteration of China? Let's be sober with our analysis since we don't want to come across paranoid and conspiratorial.