That’s not at all what Linux namespaces permit. It’s a side effect of using them that could be leveraged using something like CRIU, sure, but it’s not what they’re for and they’re not a building block for anything mentioned in the portion of their comment you quoted.
Namespaces simply make the kernel lie when asked about sockets and users and such. It’s intended for isolation on a single server. They’re next to useless in distributed work, particularly the kind being discussed here (Plan 9ish). You actually want the opposite: to accomplish that, you want the kernel to lie even harder and make things up in the context of those interfaces, rather than hide things. Namespaces don’t really get you there in their current form.
Namespaces simply make the kernel lie when asked about sockets and users and such. It’s intended for isolation on a single server. They’re next to useless in distributed work, particularly the kind being discussed here (Plan 9ish). You actually want the opposite: to accomplish that, you want the kernel to lie even harder and make things up in the context of those interfaces, rather than hide things. Namespaces don’t really get you there in their current form.