It's more about saying that his followers misunderstood jesus himself and interpreted more into him than he himself ever intended.

The muslim faith reveres mary for her virgin birth and there are miracles connected to her within her lifetime and after her passing onto heaven. I think it's more about: "yeah she was a virgin and it was god who impregnated her. But gods intentions were to birth a new prophet and not himself and the messiah."

At least this is how the quran is interpreted for many muslim scholars.