I think there is a middle ground. Sikh philosophy is new, unique and emphasizes on the formless. Gurus did away with a lot of useless rituals that some pundits emphasized. However, it is also true that the names of the formless that Gurus mention (among others) are Hari and Ram. Ram appears thousands of times in Nanak's poetry. Of course, there he means it as a formless entity. Guru Gobind too started his literary journey with Chandi di Vaar and correction of what Rudra means. Those who are hell bent on proving a unique identity often do it by ignoring the cultural history that Hindus and Sikhs shared, which I think irks most of the hard lining Hindus. On the other hand, it doesn't mean Hindus can claim the cultural identity of Sikhs. I hope someday we can all see the nuance.