I have read that there is research into DNA that can claim individuals linked to the tribe of Judah not by practicing the faith of Judiasm but by blood.....I imagine that could encompass many ethnic types of people no matter what religion they practice...
Of course, but that isn't the point.
The first thing the Indian Jews need to prove is that they practice the religion. The second thing they need to prove is a cultural heritage. The third thing, which they have refused, is genetic proof. The third thing isn't necessary, but it would reinforce their claims if they share Middle Eastern links genetically, and share some of the same genetic groupings of markers that many Jews carry, and which some Arabs carry.
They can use DNA evidence to prove their heritage has common ancestry as the Jews. That's really all they need to do.
The flaw in your logic about other people with Middle Eastern links who are not Jewish is simply that they aren't claiming immigration rights to Israel. So the issue of those people is moot.
You're arguing a completely different point than the issue of the people addressed in the article.