I’m no fan of her but how is this a shot at Bernie exactly?
If you look at the actual tweet she retweeted, it was a very clear shot at Bernie. I actually believe key figures in the party shouldn't be platforming attacks on Democrats, but it's not something that matters in the long run. At the end of the day, the only people who will care about this in a week are the terminally Online, and it doesn't change the progress that Hillary has made.
tl;dr: We can praise Bernie for the work he's doing now and Hillary for the work she has done to get us to this point.