We know there are novel viruses out there, too many to count. Even if this started in a lab the most likely reason is that scientists need to study the viruses that we will be coming into contact with as we commit, as a species, to more environmental destruction. I'm really exhausted of watching scientists get blamed repeatedly for the failures of our economic and social systems to act responsibly.
Sure, the lab hypothesis might have some weight, some possibility of being true. It's still a red herring, either a distraction from the real issues we face by accident or design, or both.