It’s not just pro-Trump, it’s denying the election was valid because their messiah did not win.
The flag was up for ”several” days – if you accept he was ignorant of its meaning(!) it’s a sign of either extreme distress or disrespect.
— ‘we now have [two] conservative justices whose spouses have engaged in apparent pro-Trump political activity.
…
Gillers … did not believe Alito knew the upside-down flag was flying, or that it was a coded message for “stop the steal”.’
https://www.theguardian.com/law/article/2024/may/18/samuel-alito-flag-supreme-court-ethics-election