Stephen he may well have been drinking Scotch but as Jennifer says the language is Scots or Auld Scots and it was not so much the language which was suppressed but the culture of the people, the music and the dress but to give two examples. Robert Burns was a remarkable man, his breath may have stopped but his voice is still heard.
Your copy of Robert Burns' A Man's a Man for A' That appears to me to have left out one line in the final stanza which when entered would make the 5th and 6th lines read:
For a' that, an' a' that,
It’s cuming yet, for a' that,
John Anderson my jo, John, When we were first acquent, Your locks were like the raven, Your bonny brow was brent; But now your brow is bled, John, Your locks are like the straw, But blessings on your frosty pow, John Anderson my jo!