It totally is safer, and I tend to agree with it in a business context. But the license itself doesn't seem to indicate that any kind of "RPC" is thus encumbered.
When MongoDB was under the AGPL, your application wasn't under the AGPL if you connected to it and asked it to do queries.
When MongoDB was under the AGPL, your application wasn't under the AGPL if you connected to it and asked it to do queries.