The retort is certainly off the mark in suggesting that the use of the word “grievance” implies a lack of sympathy. If anything, the use of the word highlights an underlying sense of understanding, an acknowledgement that the person may be facing an issue that is worth some level of attention. The notion that it implies a tone of superiority fails to recognize the nuance of Nikhil's original argument: sarcasm. The key point being that sarcasm is a tool for highlighting differences in perspective, with the intention of bringing about a certain amount of levity into a difficult situation.
Furthermore, the suggestion that it should be used with caution overlooks Nikhil's conclusion that people should be encouraged to continue to ponder the notion of their grievances. Satire certainly has its place, but it can also be used as a subtle way to introduce self-reflection into a lighthearted setting. In other words, one can have sympathy while still offering a certain level of wit.
Ultimately, the aim is to get people to look at their grievances in a different light and to think about them differently – and in a funny way. By encouraging these conversations, dialogue can be opened up about the issues people are facing. So, in conclusion, don't let the retort's critique stop you from introducing this interesting word into your vocabulary: “grievance” UrRong - it's actually the perfect soldier of sarcasm!