The veil of ignorance that undergirds the moral assertions of the left.

There is a view held that  moral assertions have ‘no objective validity whatsoever’.
Why?
For as ‘pure expressions of feeling’, they ‘do not come under the category of truth and falsehood.
 They are unverifiable for the same reason as a cry of pain or a word of command is unverifiable – because they do not express genuine propositions.
This leaves us little room for moral deliberation or for rational argument about moral issues.
What makes a moral assertion true is not anything about what it apparently refers to (the actions of people and their effects on human welfare, for example) but simply something about the state of the speaker. I may hold this moral view sincerely, but that does not mean your sincerity is indistinguishable  from truth.
 So we move on to Beyond Subjective Morality

Subjectivism  can be interpreted as the residue left over from a failed Kantianism and his categorical imperative.
There is a kind of subjective universalism in anti Trump protest and what is happening across EuropeThe anti Trump protesters in a form of frightening certainty if confronted with a rigorous argumentabout their pseudo morality with no doubt argue in their certainty that our  moral stance is  is arbitrary but we are still prepared to say that everyone else should do the same in similar circumstances’. 
However there  are various strands to the moral debate1.  amoralism  - It’s simply a question of what I want’ - denying that moral judgment can be made at all.
2.  personalism - ‘I can only say what’s right for me to do – I can’t judge for others, denies that moral judgment can be made of other people
3   relativism  - ‘I should do what’s right from my perspective, others should do what’s right from theirs but relativism has the unpalatable implication that Hitler acted rightly so long as he believed in what he was doing.4.  Universalism   faulty and  unstable, since it is hard to see how, if one’s own moral opinions cannot be supported in terms that claim the allegiance of others, it can be legitimate to impose them on others5. Relativism - 
A moral position held to be valid  must have requirements 1. have a rationally unquestionable basis, 2. consist in principles that hold without exception, 3. give an answer to any possible moral question, 4. abstract from all human interests and concerns, 5. be consistent with conscientious moral decisions,  6. determine obligations with strict impartiality.
Some defending morality, i,e the philosophical praetorian guard make impartiality the hallmark of morality.
Suitably generalised. Thus, one could say, ‘Everyone should defend his own country,’ but not ‘Everyone should defend my country.’But how one would arrive at impartiality?  Rawls’s conception in A Theory of Justice of a ‘veil of ignorance’, blotting out all information that is (according to Rawls) morally irrelevant, would be one construction, but an inherently controversial one. 
What one has in the leftist  protests is, morally grandstanding  -  a blank wall of pure assertionbut what undergirds this view is the  interminability of fundamental moral disagreements, i.e can one hold a sustainable moral view, and if so, where did that moral view come from and how is it and was it constituted.