if you come from say a "problematic country" - and you are up for a noble prize does that disqualify you?
the list goes on...
Very obviously not, on the basis that the prize is for an individual representing, at best, a scientific institution. They are not representing their country.
In the Olympics, you can compete as an Independent, thereby not representing your country of origin.
But this entire line of questioning from you seems either disingenuous or obtuse, tbh. The Israeli competitors are deliberately running propaganda for their country. There is a global media campaign to vote for them funded by the Israeli government (and before the question: No. The UK government does not provide any funding at all in respect to Eurovision, unless it is hosting it).
The very idea that the Israeli competitors would, like an Olympian from a disgraced nation, choose to compete as an independent, not associated with their country, is absolutely absurd. The entire point of their participation is based on the idea that they are representing their country, literally on behalf of their government. Your hypothetical turns this into an abstract that is shorn of the details that actually matter.
But if we are to accept generalities then, yes, it is perfectly acceptable for an individual to lose opportunity because of the actions of their nation, even if they disagree with those actions. For example, the Israeli government, funding this little propaganda exercise, has repeatedly argued that everybody in Gaza bears responsibility for the Oct. attack, and they all must be punished. This is not mere talk, because this desire has been enacted by, at a minimum, a blanket siege in the region. While Israel has decided that children should not be allowed food because they are Palestinian, you want to have a conversation as to whether an Israeli should be deprived of the right to run propaganda for their country in a singing competition. I hope you see the asymmetry in these two things. Which in itself is a side note: If your abstract moral position held, there would never be a moral justification for sanctions or for war, both of which affect all individuals of nations irrespective of their beliefs.