Given the following example:

Location(s)
 Europe / Czech / Brno
 Europe / Czech / Prague

Brno has Subnet A
Prague has Subnet B
Czech has domain cz.corp.com

Location.current = Any Context / Eurpoe (doesnt matter)

If you would select location (in the host new form) as Czech, you wont be
able to save the host, as it has no subnets.

Would you prefer to see both Subnet A and Subnet B instead? (sounds less
practical to me).