Murugan Debate

Hello Tamil Nadu, I am from Nepal. Recently I stumbled across this debate amongst people regarding the status of Murugan. I find many people who I deduce to be Tamil ethno-supremists to reject the Hindu links of this well beloved deity and claim him to be a solely Tamil god. I cannot say I believe this and even if it is true, what harm comes from us Hindus worshiping him as well? I have also seen some people absurdly claiming Hindu doctrine on his story was stolen from christian theology and that he is actually Jesus?

In Nepal's context, as far as my knowledge goes, Kumar has been worshiped for over 2 millennium. Suffice to say we do have a pretty long history is his worship as well albeit probably not as long as your people. In our folklore, he along with Ganesha are the two deities first worshiped before anything else. We have a small circle made of brass or stone called Pika Lukhu, which we worshiping as Kumar every morning and evening before the beginning of that day's bi-daily prayers. He is also specially worshiped on a day called Siti-Nakha with grand rituals and street processions.

So my question is this. Why do people solely want to claim Murugan? Can we not celebrate him together in our different ways?