He went too far in declaring it to absolutely be from the facility, but it's not a conspiracy theory to think that it could be from the facility. There's a significant chance that it did, which is why many people, including highly respected scientists and governments are looking hard at it right now.
This is what I've heard as well.
What I'm about to say is NOT political, but simply restating what I've heard and read. I'll post an older, but good story on it below from NPR.
Initially, the international community did NOT want to say anything about where it may have come from. They needed China's cooperation in order to do the actual investigation. President Trump (at the time the US President) decided to blame China and say it came from a Lab. This was probably based on intelligence he received at the time or reports regarding suspicions that this was the origins of the virus. Instead of keeping it quiet in order to help insure the ability to do a true investigation into the virus's orgins, he broadcasted his accusations of this publically.
This made China uncooperative. This made doing an actual investigation impossible. If it came from a Lab or had origins in the Lab, the investigators no longer had the access to actually find out. In fact, this hindered their investigation into the origins of the Virus almost impossible on all fronts, from figuring if it came from a natural source, where that sources, was, or any other theory.
Thus, they have NO hard evidence (or did not) on it's origins because they were not really allowed into China to do a full investigation in the manner which they would have to figure out the mystery. This means, at this time, we still do not know where the virus actually originated from, though there are suspicions on several fronts.
Relations with China also makes it a sensitive matter to investigate.
NPR Theory that COVID Came from a Lab takes New Life