I'm not sure why you are posting this. First, in general, the CDC does not give advice to the general population they provide information to healthcare providers. Like most federal agencies they work through intermediaries not with people directly.
To the substance of your post, the CDC says right here: https://www.cdc.gov/std/tg2015/pen-allergy.htm That penicillin is the only treatment for advanced or congenital syphilis. And again here: https://www.cdc.gov/std/tg2015/syphilis.htm they say it is the preferred treatment for syphilis.
If you want the straight dope on what the CDC said about Penicllin-G, go here: https://www.cdc.gov/std/treatment/drugnotices/bicillinshortage.htm Basically, they are telling *doctors* to stop prescribing it for things other than syphillis, since it is the preferred treatment for syphilis. If you want to give someone grief about there not being enough penicillin-G, how about giving it to Pfizer, the only manufacturer, who refuses to manufacture enough!