Usage of Data - Taking data offline


If have a client company A and they want to know who follows Company B but not company A, is it within the usage terms to use the API to return follower lists (and details on Friend/Follower volumes etc.,) for both companies and extract them to an offline database for analysis?

I know there are applications such as FollowerWonk who do this sort of thing online but I want to be able to do this to return the data offline and using my own API for access.