It sounds like they called him in to give his opinion and he did that. I don't see how that is unhelpful. An employee's job is not to ensure that the employer gets its way no matter what.
But I tried not to be a jerk at all. Every time they asked me about a different aspect of the system, I could just say something like, "We used standard software engineering techniques using an algorithm built in to [common language] to sort things here. It's a fairly common approach to this sort of problem." After a statement like that, the patent lawyers had very little to pull on. They'd move on to another aspect and I'd give a similar answer.