I don't! imo this kind of statement is very calculated. I wouldn't say it's a sign that Clyburn wants or expects Biden to step aside but I do think it is a sign that it is being considered and he's giving the party notice that Harris would be the replacement and he expects no funny business.
Right, but the only part of the quote that's circulating is "'I will support' Harris if Biden 'were to step aside,'" which people are, in fact, using to suggest that it's a sign that Clyburn wants or expects Biden to step aside
Also important is how Mitchell phrased the question. If he hadn't said "I will support her", the story becomes him opening the door for others. Instead, we get this cycle out of it. Easy to read it as a deeply cynical approach to asking the Q.