That person on github is misunderstanding both Poettering and the ntp.org's policy.
MatejLach's elaborated on Poettering's point of view for that matter. https://github.com/systemd/systemd/issues/437#issuecomment-1...
* NTP Pool welcomes open source projects to use their servers
* They want vendors to register a vendor prefix
so there are two options, either systemd is a vendor, and can register and use systemd.pool.ntp.org, or it isn't, and can use pool.ntp.org
They could (register a "vendor zone") and use "[0-3].systemd.pool.ntp.org". They can, technically, even use "[0-3].pool.ntp.org", but the NTP Pool Project is saying they cannot use [the specific hostname] "pool.ntp.org".
That last part is what people are apparently not understanding.
Also, OpenBSD blatantly ignores it and uses "pool.ntp.org" anyways.
From the Github comment you are referencing, dannyperson states, "When NTP Pool warns that pool.ntp.org should not be a default, this warning is directed to vendors, not open source projects." but the clause from http://www.pool.ntp.org/en/vendors.html IS talking about Open Source Projects. The heading is "Open source projects".
What is the difference between a default setup and a default configuration?