As far as the Pixiv post is concerned, it's only tagged as Yuri, with no mention of futa or trans. KanaMari's sex position and Yoshiko's condom joke can easily be attributed respectively to missionary grinding and Yoshiko being a huge dork. There's nothing in the dialogue that directly hints at there being dicks as far as I can tell.
Agree, I was puzzled what exactly caused the tag after reading it. Just to add that condoms are usually a lot easier to get than dental dams, so if you're going down the safe-sex route (concerns about which are explicitly mentioned in the dialogue), condoms are a seriously useful tool for two women as well*. Hence the presence of a condom does not really point to anything specific.
Seeing as Pito has no problems tagging stuff as futa if it should be considered as such, it does sort of stand to reason that this one is therefore not in that category.
*cut the tip off, cut along one side, unroll -> pre-lubricated dental dam