Upside-down flag is the universal symbol of distress. It has also (ironically) reportedly been used as a protest against the decision that overturned Roe v Wade. I know the date and time of when the flag was flown matters, but this is ridiculous.
It was also common after Trump was elected in 2016.
Exactly my point, there's no need to read into this as anything more than a statement of displeasure at the result. Now, that does raise another question about whether that kind of statement is appropriate from a Supreme Court Justice, but it's not the same as supporting "Stop the Steal".