@Dave they will say that as you have left the site created in wordpress unpatched which is nothing to do with them.
Worst case scenario for all you know the site when hacked could have been loaded with a trojan which tries to infect other devices that visit the site and/or they try to steal your identity with key loggers etc.
Nat, a site may look ok but how do you know for sure there is no malice code been left there?