You just put the problem into focus. Trump pushing the lab leak hypothesis and using the term "China virus" is indisputably a xenophobic dog whistle to a racist subset of his base. But that doesn't mean the lab leak hypothesis and any discussion of it is racist, and based on what's been uncovered since, it's certainly not a baseless accusation.

Trump has used this tactic effectively many times in the past: he says something that makes sense ("we need border security") in such a racist and distasteful way that causes the opposition to kneejerk react against whatever policy he's proposing, forcing them to take a position that's at odds with common sense ("border walls are racist!"). It's possible he may have had some classified information about the lab leak being a feasible story, but I also wouldn't be surprised if it was just one of the thousands of things he blabbers uncontrollably about and this particular one luckily happened to have some truth to it.