They aren’t running a COVID timetable because of an ACTUAL shortage of train crew. It (and others) were instructed by the DfT to put in a COVID secure timetable by the 17th Jan that would run, even if 10-15% of their staff had COVID. If staff were spare, all the better because it would guarantee the advertised reduced service would actually run. This service was due to run until the end of Feb and then it would revert to the December 2021 TT, if resources allowed it.
The DfT now want to bring that end date forward by a week or two and TOCs are under DfT instruction to manage overcrowding by inserting extra trains, if they can. Most TOCs can’t just switch back to the December 2021 TT at a moments notice, because of rostering, so it will be interesting to see how SWR manage this, with disruptive engineering work, a shortage of trained crew and the 701 saga. 21st February has been quoted on the railway grapevine as the likely date that the DfT currently want SWR to revert.