Seems like a great candidate.
How many invasive species have managed to make native species go extinct ?
It just takes one accidental escape from the lab.
It's hard to believe that this type of experiment is legal - it seems potentially far more dangerous than experimenting with known deadly pathogens like ebola, hantavirus, or gain of function research. Here you have people custom designing viruses that no species on earth has ever encountered before or developed a defense for.
What could possibly go wrong ?
We could go extinct is what could go wrong, or maybe just wipe out some other species that we're dependent on such as bees, or rice, or ...