I would suggest there is a difference between seeing Jesus in toast, or Mary in oxidized glass and seeking Jesus.
Seeing Christ in a grilled cheese sandwich or in clouds for that matter, as was the case in the early 20th century via a photograph that was acclaimed for years, is a psychological phenomena known as Pareidolia.
I think if someone see's God, or Jesus, or even Mary, in common place things or in nature, that it may be a sign that their soul is hoping to find an avenue wherein they can then pursue the real thing.
One never knows. However, the scripture tell us that Christ's body was wrapped when he was placed in the tomb. And if this shroud happens to be that wrapping and the image upon it happens to be able to be identified as that what could not have been forged or faked in the early centuries when it was first discovered, how can we say an all knowing God didn't know that one day human technology would find a way to prove to even the atheist that Jesus is real?
Because for those naysayers who are the type who say, I'll believe it when I see it, this could very well be a means that shows the world a risen Christ was once a man. Just as God's word tells us.
As for the charge of pagan idolatry, I don't know anyone who worships the shroud of Turin. Though its mystery has intrigued people for years. And now its mystery is a little less so per this latest research.
I think if we condemn what may be the miracle on the shroud as pagan idolatry we might wonder what we're doing if we wear a cross pendant? Displaying a notorious sadistic Roman capital punishment device that took our Lord's life on our person as we call ourselves Christian.
Jesus raised the dead, cured lepers, made the blind to see. I don't think it impossible he could have imprinted flax with his spiritual energy as his soul departed and then left the body in the tomb he only rested in for awhile.