The issue at present is that the government has refused time to debate a substantive motion in the House of Commons.
What good is a mechanism that can be used to effectively shut out any questioning?
Imagine you are the man that approached the king. You have some very pertinent questions. The RF are not forthcoming. Your MP didn't reply to your letter or sent you some copy-and-paste platitudes. The government is hoping it will all go away. What options do you have? You are not a terrorist and perhaps not even a republican. Just a decent person watching in horror as some pretty serious allegations are levelled at the RF. What do you do?
This person approached Charles with his questions. As awkward as this might seem I think it was a missed opportunity for Charles. He could have had a stock, polite answer prepared, or indeed he could have engaged with the "heckler". Instead he ignored it all while some onlookers went on "shush, least said soonest mended" mode. A different person to Charles could have seized this opportunity and turned it around. Instead the whole scene made him look weak and out of touch.