"Necessary for performance of a contract"
Yes, there is that provision within GDPR. However; the data collected/published has to have a lawfully justifiable PURPOSE, and the PURPOSE has to have a LAWFUL BASIS FOR PROCESSING - in other words they are using circular logic to try to confuse and I don't think the Courts are that thick.
The contract you're trying to use as a Lawful Basis for Processing has to be a legally binding contract and when it isn't, any clauses which are not lawful are discarded as if they're not there; THAT much is written into Contract Law and backed up by relevant Case Law.
ICANN have been lazy and they ARE going to pay the price for that. If I as a layperson can understand this, so can they - and I hope their attempts at obfuscation and delay are rewarded with a robust legal response.