You are correct that cauliflower must be checked for bugs. But this is a store bought product made with pureed cauliflower. When cauliflower is pureed so are the bugs if there were any and that would deem the cauliflower ok to eat.
Pureed cauliflower that you know has bugs in them would not be permitted. It is only in this case that the pureed cauliflower is ok since we don’t know for sure that there were bugs in them.