As usual, Jehovah's Witnesses take a scripture out of context and assign a meaning to it. If you read the full context, it would or could seem to indicate that Jehovah is doing the forgetting and not calling to mind his peoples past transgressions. Verses 16 and 17 should be read together:
"16. So that anyone who seeks a blessing for himself in the earth, Will be blessed by the God of truth, And anyone who swears an oath in the earth Will swear by the God of truth. For the former distresses will be forgotten; They will be concealed from my (Jehovah's) eyes, 17. For look! I am creating a new heavens and a new earth; And the former things will not be called to mind, Nor will they come up into the heart." Interestingly enough, verse 16 is cross referenced to Isaiah 12:1 which states: "In that day you will certainly say: "I thank you, O Jehovah, For although you were angry with me, Your anger gradually subsided, and you comforted me."