I guess there are two different sorts of advisers they are talking about. "Vocal complainants" seems to refer to the former News Corp lawyer who is advising the case. Advisers who work with competitors is presumably referring to technical consulting firms working on the case. It's not clear which competitors they work for, but presumably Google is not objecting to a consulting firm that also works with, say, Costco, on the theory that Costco is a competitor in the electronics sales market. That would be pretty thin, and Google would have no reason to object. Presumably Google is referring to a consulting firm that works heavily with e.g. Microsoft or Oracle.