Hi Alpha,
What about all those otehr christian sects that lived long and believed that Jesus was never crucified?
It could be a valid reason, maybe same reason they wanted John dead, they also wanted Jesus dead as well.
There seems to be a little problem with your gospels, all dependent on account witnesses, every gospel that was written depended on them, even the ones discarded, lots of people said too many things about Jesus, all taken from more than 24,000 documents.
The Sunnah for example is chained, every one who delivered A Hadith is mentioned, every person is studied. Unlike your Gospels, they could be simply called Ghost Writers and Ghost account witnesses, because you can't PROVE what so ever who wrote them AT ALL.