If he left the Catholic Church and became Episcopalian, it’s not likely he will care what the Catholic bishop permits or denies. From the Catholic perspective, any Eucharist he celebrates will be illicit, but I somehow don’t think that will actually concern him.
That said, the consecration of the Eucharist is a power of Order, not jurisdiction. That means, if a former Catholic and now Episcopalian/Anglican priest consecrates the bread and wine according to, say, the Book of Common Prayer or the English Missal, with the proper intention, yes there will be a true Consecration at that service.
What he will NOT be able to do validly though, is absolve in Confession, except in danger of death because that Sacrament does require proper faculties as well, which he would no longer have.