The issue is the opposite, because people use non official communication channels it's hard for regulators to get the information they need, and it can be taken as the bank hiding things, which leads to fines. It's in the article:

This could result in the breach of regulatory rules on recording all business communications, leaving little room for oversight by authorities to take action in case of compliance concerns.

"Banks use a wide range of approved channels to communicate in compliance with regulatory obligations,” a spokesperson for the bank told Bloomberg. “HSBC, like many other banks, reviews and adjusts functionality on its corporate devices as needed.”