Well, we keep replying and getting no closer really.
They keep saying what current RIPE policy is, and that according to current RIPE policy the current policy applies to old assignments as well.
However they continue to refuse to explain any legal mechanism by which our customer is subject to RIPE policies in the first place (current or old).
Even if the customer agreed to RIPE policy back in 2003 it is not clear that the policy they agreed at the time bound them to newer policies. i.e. that the 2003 policy allowed for unilateral changes to policy later.
I suspect that at the end of the day it will just be simple blackmail - my customer having to sign under the duress of a threat to disconnect their Internet.
We'll keep trying to get a straight answer out of them. They could at least have the courtesy to admit that it is just blackmail and not pretend that their policies apply by magic.