Form asking for SSN and DOB over port 9443

I was recently getting help from an agent over Xfinity's chat, and at the end they gave me offers of different services.

The agent gave me a link that uses network port 9443 instead of HTTPS's usual 443, and asks for my full SSN and date of birth.

Why port 9443? I can only think of poor reasons for this. Of note: many networks block ports above 1024 due to security concerns.
Why ask for SSN and DOB? Account verification can be done in less invasive ways like 2FA.

Here are quotes of the responses the agent gave. These are nonsensical in that they misunderstand the question.

Please be assure. Nothing will be port.
Its a secure link generated by Xfinity. When we generate the link for any company. It required numerical and alphabats.
There will be porting any number.