That's exactly why I used it. A nice quiet space, comfy chair and wi-fi. I never cared what it cost, if I'm flying privately I just paid thousands to fly so the train fee is meaningless, or on business I expense it. If I want the TTC experience, I know where to get it. If the UPE becomes just another jammed commuter train, I'll take my private car or Uber to the airport.
IMO, the UPE should never have included those middle stations. The Paddington to Heathrow train has no stops - that's the model I want.