I think that the subject of the e-mail is very self-explanatory.

With some analysis of what is running over our network, ISP or ITP, we will be able to see some TCP/UDP(mostly UDP) packets with source or destination to port 0.

I can think of a genuine use of it.
(Maybe someone cloud help me see what I'm not seen.)

So I have two questions:

a) Should an ISP block that Kind of traffic?
(like anti-spoofing on BNG/B-RAS)

b) Should a Transit Provider block that Kind of traffic?