It’s because not everyone is federated with Beehaw and if the instance isn’t federated with them you won’t see posts from their users. You can see which instances are federated with your instance by going to servername.whatever/instances. So for us we would check at startrek.website/instances and then you just search for beehaw. If it shows up in that list then you will see their posts. If not, you won’t.
It doesn’t make sense for her to say that. According to google Robert is 1.84 meters tall and Sarah is 1.7 meters tall. That’s 1cm over 6 ft for him and just about 5’7" for her. Why would he stand on an applebox? Does he need to tower over her? Also looking back at the episode he appears about 5 inches taller than her in most shots where they’re standing together so he doesn’t appear to be using an applebox. I think she is misremembering.