I think the idea is that Jesus was saying secular authorities should be regarded as authorities in secular affairs, while religious authorities / God / the church should be regarded as authorities in religious affairs. At least that's one read of it. So the commenter defers to the illegality of piracy as determined by secular authorities, and doesn't pirate, as a way of respecting (his/her interpretation of) Jesus' (reported) teaching.

Which in my view is a fair approach to life, but hard for me to adopt personally.