They say that the age of consent being 16 only applies to children who's parents sign for emancipation, which they absolutely will not do.
They're mistaken. Age of consent and emancipation are completely unrelated.

That said, if they don't want you seeing him, they CAN (and sounds like they WILL) make your life - AND HIS - extremely miserable. For instance, having you slapped with a restraining order, for starters.

If they want you to stay away, you stay away. Until he is of legal age to move out, support himself, and do as he pleases, they may as well be as gods to him. They hold the ultimate veto power.