(a) what is "hate speech" is a vague term to be filled by whoever yields the power to define it (could be anything from talk against religion, to conservative worldviews, to class-war ideas, to racist beliefs, to complaints against politicians, and so on).

(b) what is a minority can also be vague and politically determined as opposed through raw numbers, and the power of a minority could be more than its size tells us (e.g. the 1% is a class-based minority, but most don't have an issue with going against them. Similarly, in certain cases it's one or more minorities that have the power against the majority - e.g. the fewer white-spanish descendants over indians and mulatos in some Latin American countries, or the white 20% against the blacks 80% in appartheid South Africa).

So, no, it's not clear cut that it's "in a society's interest to limit hate speech against minorities".