This is as if he said, let him ask the Lord to forgive him, and he will forgive him being so asked.
The taking away of an objection: indeed all iniquity is comprehended under the name of sin: but yet we must not despair therefore, because every sin is not deadly, and without hope of remedy.
Many worry about committing the unforgivable sin. I think it is safe to say that if you are worried about committing it that you have not done it. Instead of worrying about the unforgivable sin, we should be thanking God that He has forgiven us of all the multitude of other sins. Our glass is not empty, it is running over with God's forgiveness!
This brooding over the possibility of committing the unforgivable sin is Satan's way of causing doubt, depression and self absorption. But these verses talk about praying for others not turning inward. The best antedote to depression is praying for others and getting outside of ourselves.