I just had an extraction/implant placed & was told not to rinse with saltwater.

it is better to use an antibacterial prescription  mouth rinse = peridex (chlorhexidine) Implant related surgical procedures are more extensive than simple extractions or flap surgeries.  So more attention is needed to post op care instructions ....Salt water will not be strong enough to decrease the bacterial load in the mouth. Also the cleanliness of the water, and the concentration of the salt used,  can not be controlled....

My recommendation is to follow the instructions you received from your surgeon.  Did you get written post-operative instructions?  If you want to verify what you heard from the office manager, perhaps by speaking with your doctor or his surgical assistant, that would at least put your mind at ease.  Usually, the day of the surgery, we recommend NO vigorous rinsing.  The second and third day we have patients use 1/4 tsp. of salt dissolved in 8 oz. of warm water and gently rinse with portions of the solution, taking five minutes to use the entire glassful.  This can be repeated at least two or three times daily.  Keeping your mouth clean after surgery is essential.