Not really. The dangers of hydrogen are exaggerated. The famous one is really more about burning fabric than burning hydrogen. It's no more worrisome than large quantities of gasoline, which we deal with all the time.
And even if there is a problem, it's a weather balloon. It's designed to be disposable. It floats away from people. If it is anywhere near people, it's because there's a leak -- which means the gas is already escaping, and will rapidly be gone.
