I'd more figured it's because Kohai-chan is dressed asm, you know, Misato.
Kouhai-chan being dressed like Misato only answers the question of how the post itself is related to Evangelion; it doesn't address the issue that Rikei-chan does not look like anything from the franchise in question that the average person with some awareness of it would readily recognize or even be able to figure out from a casual search. The image of Ritsuko Akagi that Rikei-chan's look and action is based on is quite obscure.
Kouhai-chan being dressed like Misato only answers the question of how the post itself is related to Evangelion; it doesn't address the issue that Rikei-chan does not look like anything from the franchise in question that the average person with some awareness of it would readily recognize or even be able to figure out from a casual search. The image of Ritsuko Akagi that Rikei-chan's look and action is based on is quite obscure.
Rikei-chan doesn't do cosplay. she roped Kohai chan into her group to do cosplay.