Post on /r/eero with some questionable logic?

Hey there, Can someone with a bit more networking knowledge take a look at this post?

https://www.reddit.com/r/eero/comments/m0l7nu/does_eero_block_wlan_to_lan_traffic/?utm_source=share&utm_medium=ios_app&utm_name=iossmf

The flaired Eero developer goes off about topology, and isn’t very helpful, but I am trying to understand what they are talking about.
It sounds like their Ethernet backhaul is doing stupid stuff with spanning tree and the master unit needs to be “upstream”?

Aside from the /r/iamverysmart material, is there something I am missing? If all the access points, in bridge mode, are plugged into the same switch, why would it matter that the default route goes through the Eero or not? It would not change the path the backhaul packets take to get from Eero to Eero. (I might be too tired to be thinking about this.)

Appreciate the assistance with my curiosity ;)