Those aren't false positives; they're results he hasn't yet inspected.
I wrote a longer reply here: https://news.ycombinator.com/item?id=47638062
I wrote a longer reply here: https://news.ycombinator.com/item?id=47638062
It's not a XOR
If the claim was instead just "a good portion of the hundreds more potential bugs it found might be false positives", then sure.
The hard thing is reducing detected crashes to well-formulated test cases that help rather than hinder maintainers.