This is right that there is a Sarsuti river parallel to Ghaggar, In another hymn of Rigveda, Drishdvati, Apaya and Saraswati are shown flowing parallel, Drishdvati and Apaya flows in Harayana, near Kurukshetra, Apaya in Sanskrit means with "less water (AP)" which is true, in case of Apaya flowing near Kuruksheta, mostly a seasonal river.Not sure why we are trying to prove Ghaggar as Saraswati or not, when we already have Sarsuti/Saraswati existing parallel to Ghaggar.
You must remember that Indo-Aryans replicated the geographical terms a lot. If original Saraswati was in Afghanistan (Helmand flowing into Hamun), then it was replicated to a tributary of Ghaggar during Vedic Age, then to other parts of India: Allahabad, Gujarat and Bengal etc.
If original Sapta Sindhu was in Afghanistan, then it was replicated to North India during Vedic Age and then to entire Indian Subcontinent, as today the Sapta Sindhu is Sindh, Jamuna, Ganga, Narmada, Godavari, Krishna and Kaveri.
Similarly, lot of other geographical entities were replicated.
He refuses to accept that Vedics kept replicating place names, god names and river names that they admired, they admired the the word "Bharata" vey much, it is another name to God Agni and get's repeated in Rigveda for more than a dozen times, this is found only in Indian Sanskrit and that is the word that gives India it's current name "Bharata" which shows Vedic Aryans originated in India only.