Again all that extra info is meaningless... he is the parent and as such has the superior right to claim his child.
HOWEVER...before anyone files there needs to be a conversation between him & the grandparents ...if they make more then he can allow them to claim the child if it is better for all parties combined BUT he is not REQUIRED to let them ... have them read this thread which quotes the IRS rules and/or consult with their tax preparer.
