That is false. They do in fact hurt SEO because your "vBulletin Mods and Addons" link is an external site-wide link. Your first link is set to nofollow while the following link to "vBulletin Mods and Addons" is set to follow. I'm assuming this is done on purpose to gain SEO value out of the links. Seems odd to me that even purchasing the product doesn't allow you to change this and you'd have to purchase a whole separate package to remove the links.
I'm obviously okay with keeping the copyright but I'm not okay with keeping the links, especially if they are dofollow.
How exactly does making it nofollow affect the copyright notice? The only purpose I'm seeing is for you to steal our link-juice.