GP was not well-phrased. I think they meant "the first detection of a MACHO candidates could be via a WIMP detection" (a black hole planet 9 would likely be in

GP was not well-phrased. I think they meant "the first detection of a MACHO candidates could be via a WIMP detection" (a black hole planet 9 would likely be in the last uneliminated sliver of MACHO candidate space and we'd see it via WIMP annihilation)