Alright, lets assume for a minute that the Mccanns didn't have access to the E-fits for whatever reason. They'd been withheld due to none payment by whatisface, or they'd handed over all copies to various police forces*. Why then didn't they try to get more copies when they are faced with someone else suppressing them?
They were happy to take LC to court to try to get access to information about the investigation after all. These were E-fits which their own fund had paid for. Why weren't they shouting on top of their voices that someone else was suppressing vital information that could lead to Madeleine being found?
Even if they didn't think the E-fits were likely to be of the abductor, as someone (davel?) pointed out on a different thread the other day, you grasp at straws when your child has been abducted, you try anything. They released other e-fits, so the argument that they didn't have the authority does hold water. I can't see a legitimate reason for these e-fits not being published.
*I haven't seen a reliable source for these ever being handed to a police force.