Upvote:5
This theory is not at all plausible.
Judas the Galilean is known to us from 2 sources: Luke (Acts 5:37) & Josephus (e.g. Antiquities 18.1). Both sources also make reference to Jesus and know Him as a distinct individual.
Thus the problem boils down as follows:
Additionally, Judas the Galilean died in approximately AD 6 (though there is a minority view that he died a few years earlier). Jesus was put to death under Pontius Pilate (this is established by both Christian and non-Christian sources); Pilate didn't come into office in Judea until AD 26.