oh sure whatever was we thinking leaving those techs just hanging there and not properly requiring you to have unlocked everything first. how dare we miss a few that are not properly gated. we should just add it to the right tier after magically noticing it wasn't placed correctly right after we just balance all the machines and we just fix all the deadlocks and we just do a dozen other things.
i get it its annoying that it wasn't properly set in the right places in the tech tree. its not intended but there are hundreds of techs to keep track of. a few get misplaced. maybe they was never right or something got moved afterwords or something. its hard to say but we've already fixed several of these techs unlocking things in the wrong tier issues. just let us know and it'll get fixed.
TLDR: shit gets missed and this happened to be one of them and for some reason your the first one to report it that im aware of. im sorry it was an inconvenience but just simply let us know and we will sort it out.