My best guess is that because DeSimone was with Jimmy Burke, and Jimmy Burke was with Vario, and because Burke hauled in boatloads of cash for not only Vario, but important people in all of the families, Desimone was safe as long as he was useful. Once he wasn't, he was turned over to Gotti.
"...the successful annihilation of organized crime's subculture in America would rock the 'legitimate' world's foundation, which would ultimately force fundamental social changes and redistributions of wealth and power in this country. Meyer Lansky's dream was to bond the two worlds together so that one could not survive without the other." - Dan E. Moldea
