Interesting that the court choose to use the word "promote" in its decision - because it has two not-fully-congruent meanings in the English language. One would be in the sense of "Advertise" - that is, "use our software and steal songs!!". The other meaning of promote means "to assist" or "to allow/make possible", "to help bring into being" - for example, "some tax policies are designed to promote public investment".
Hence, in the second sense, they did answer the real question in front of them - and ruled more strongly in opposition to grokster. In that sense, its software does "promote" - that is, makes easier or makes more possible - the sharing of copyright-violating content.