So in that quote from Twitter, someone needed to get home from Waterloo to Wareham.
The advice was not to travel, and to claim a refund on the ticket.
What is someone who is in London but lives in Wareham supposed to do then?
Just pay ££££ for a hotel and meals in London for days on end until Network Rail can get round to repairing the damage, or SWR can condescend to arrange ticket acceptance on the obvious alternative route from Paddington via Reading and Basingstoke.
Indeed, travelling from Paddington via Reading and Basingstoke to places like Winchester, Southampton... etc is a permitted route according to the ATOC routing guide, so the customer should have been advised of that in the Twitter response.