Not only it is plausible, it's very very likely. What are the odds that a lab that works on gain of function of Corona viruses is the exact place where the epidemic started?
The "exact place" the epidemic was discovered is in Wuhan, which is also where the lab is. That's a correlation, and clearly worth investigating, but it's not in and of itself proof.
I was originally dismissive of the "lab leak hypothesis", in no small part because of how quickly it got caught up in politics. I'm less so now, but I do think it's important to remember that when we ask "how likely is it that a novel coronavirus epidemic would start in a city that also has a laboratory working with novel coronaviruses and it just be a coincidence," the answer may be "not very" if the city with the laboratory is the size of, say, Frederick, Maryland (78,000), but "maybe more than you think" if it's the size of New York City (8.8M).
The lab leak idea bears further investigation, but "authorities have been too dismissive of that" shouldn't lead us to assume "well, it was obviously a lab leak."
Also: how many laboratories working with novel coronaviruses are there in the world? How concentrated are they?
I don’t know the answer, but it could well be that a significant fraction of the population of China (or the USA) lives in a city with such a lab, making it not too unlikely that the first patient will be found in such a city.
Wikipedia has a list of all the biosafety level 4 facilities.
The answer is around 30 active sites that deal with threats as serious as the Wuhan facility. Of those, less than half work on viruses, and even fewer do GOF work.
