That is almost equivalent to saying I have designed a new airliner but haven't tested it before it went into service.
No the functionality test is to show the SB has been properly conducted on each individual aircraft. The testing to allow the issue of the SB had already been done by Boeing.
The airline industry is probably the most regulated industry after the nuclear power industry.
Thats part of the problem, airlines do not understand the hazards they face and how they are managed - if they are good they just follow the rule. If they are bad they just try to avoid being caught.
A proper safety case to control the release of unairworthy aircraft is what is needed.