Hm, fair enough actually.
I have decided that the Culture would not Sublime themselves (since they are suspicious of it). And that the 40k does not have the Sublimed that exist in the Culture is part of the assumptions.
Only a small set of ships come over. The Sublimed don't.
If you're referring to the Chaos gods as a kind of evil sublimed, they are a very limited kind of sublimed in that case.
The sublimed in Culture-verse were stated to start off by doing things like moving entire constellations. They could squish the Culture in an afternoon if they feel like it except that the other sublimed would stop them.