Pretty typical Reimu bashing, you can see this on /vt/ any time she streams. She's an easy target since she's the least popular EN and is friends with the most popular EN. The least popular members of each female wave in general (Finana, Petra, Reimu) tend to be the ones who get picked on by fans of the other members on /vt/ and the like.
Vox to me doesn't seem like someone who would just be open to being used in such a mercurial manner, and Reimu has said on her member stream that the 3 people in Nijisanji EN she'd "put her hands in the fire" for are Petra, Ike, and Vox. Them being actually really good friends is not hard to believe. People mistake her shouting and whatnot as hatred, when it mostly just comes from the fact that she's a Latin American woman.