How does he know???? Because events at the island and the pic of the prince there are all over the news.
Many photos of Prince Andrew peaking out the door and leaving the NYC Epstein mansion (the one he got from the Victoria’s Secret owner— who furnished the chicks no doubt underage, one more source). Annnnd, then there is the painting of billy cokenose clinton which was in the entry foyer (and seized as evidence) in a blue dress and high heels. billy boy being a regular at various epstein locations (out west, don’t forget that property, and US Virgin Island with the dungeons, and tons of evidence collected by the FBI/DOJ (all covered by the UK Daily Mail).