As you say, doesn't make any sense, don't you just love fleet bosses.
As a rule we leave our IRS on all the time, never get switched off, unless the plane is going to be de-powered, to give them longer life, and for flight plan/wind downloads, helps if plane knows where it is.
As for packs on/off. I think all Trent 330's must take off with packs on to help prevent stall/surge at low speeds with high thrust..