Taking Tesla's statement at face value, let's look at some numbers.
There are around 139 million homes in the US[1] and there are 2900 home clothes dryer fires reported each year[2]. This gives a rate of one dryer fire per 48,000 homes, annually. Tesla says that they have "less than" one thermal event requiring emergency response per 10,000 installs. So, using Tesla's figures, a Tesla solar install is 5x as likely to require an emergency response.
But what about the results? home dryer fires cause "an estimated 5 deaths, 100 injuries, and $35 million in property loss." While Tesla solar installs have not resulted in any deaths or injuries they are not installed to anywhere near the scale of all homes in the US, but if the home dryer fires were down rated to Tesla's level it would work out to an estimated zero deaths, zero injuries.
I don't think the cited Tesla numbers are any cause for celebration. If it was 0.1% of 1% it would be "better", but it really needs to be far less frequent than that. While the "1% of 1%" is a facile sound bite and should not be taken too seriously if the real rate were around "one in a million" then I think they would say that.
1)
Numbrt of houses in U.S. | Statista
2)
Clothes dryer fire safety outreach materials