I'm sure some good can be found in the works of Martin Luther before his apostasy.
Likewise, Judas, no doubt, said and did commendable things before his betrayal of Our Blessed Lord...
While we're at it, Lucifer had much to recommend about himself before his Great Fall.
The point being that there are some whose ends are so evil, whatever good that may have come before is rightly eclipsed forever. And promoting drug use, occultism, sɛҳuąƖ immorality, and penning the Materialist-Atheist anthem par excellence ("Imagine") absolutely constitutes a sufficently evil end to warrant forever turning our backs to the (extremely minor) "good" of having written a few catchy pop tunes.