Lots of good points made here. Many pro-EU Scottish nationalists project their own views onto Catalonian separatists which aren't actually common views in the movement.
Many Catalonian nationalists are anti-EU and a common insult that the nationalists call Spaniards means "mongrel". The purpose of the mongrel insult, more often used against Andalusians, is implying that Catalonians are pure white Europeans while Spaniards are mixed with the Muslims who formed Al-Andalus. Quim Torra himself has made very similar comments in the past and openly talked about Catalonian racial supremacy.