They must have known about this when they started the program; obviously it isn't a concern to them.
And the article is incorrect that a boarding pass can be modified and still get PreCheck; in practice, when a boarding pass signature scans as invalid, a person is either allowed to proceed through regular screening or to get a new boarding pass and try again (as it is a print-quality that causes this problem).
There are some ways the boarding passes can be modified and still get PreCheck LLL outcomes. But then to succeed with that requires relying upon human errors to take place. [Some human errors have very high frequency of incidence while others don't.]