Why would they do this,
"after a cyberattack hit one of its customer support subcontractors"
How can outsourcing customer support be viable? Not only is the company paying for the staff providing the support, they are paying the contractor's layer of parasitic management, insurance and funding whatever poor choices they make for locations and infrastructure.
Some a company does on a limited basis can be a good place to outsource. Customer support is something that goes on 24/7. It's also the outward face of the company to the customers they already have. A truism in business is that it's less work to keep a customer than to attract one. It's also easy to turn a customer into negative publicity with poor support.
Some big companies aren't going to care as they can't afford to provide much support and still be the "low price leader" and they'll also get taken advantage of by the masses of unscrupulous. Even watched a video on somebody that's bought a pallet of Amazon returns? Plenty of bricks in returned xBox's and Playstation's. Lots of abused power tools that got swapped for new/shiny with the old one sent back as a warranty claim.
Customer support and relations is one of the most critical functions a company can have. To outsource it and then have that contractor leak the information is criminal and should be treated as such.