It is a deceptive article. A dealer going bankrupt wouldn’t have an effect on the securities in your account (it may have an effect on the money, however usually money is swept right into a cash market safety day by day, and money is protected by SIPC to $250k). Securities will not be belongings of the agency; it’s merely the custodian of the securities. Collectors of the brokerage agency wouldn’t have claims towards shopper securities; they might solely go after the agency’s belongings.
SIPC safety would come into play if securities have been stolen out of your account. Each brokerage agency I’ve ever handled buys further insurance coverage as much as the tens of hundreds of thousands per account to guard shopper belongings from theft.