All Opensim based worlds are grids simply because that is how they are structured and they are all capable of supporting more than a single region in that "grid." Calling a grid a standalone or mini grid because it is not in grid mode doesn't change the way in which it is accessed or looks and feels once in the world. All Opensim based worlds look similar and function similar because they use the same viewer and run on Second Life protocols.
Arguing that a grid is not a grid unless it is a registered company or charitable none-profit is basically the same as the Second Life business model which has a vested interest in confining membership for the purposes of containing a protected financial system or perhaps under age persons. But, generally, it is to keep people and content confined.
The right way to look at virtual worlds is like web sites which can be small or large, restricted membership or freely accessed by surfing the Internet. The Opensim platform code is the nearest thing to a 3D web we have in that it functions very similar to the 2D web in terms of access. The 2D web uses hyperlinks so users can surf from one web site to another with a mouse click and, similarly, the 3D web based on Opensim uses hyperlinks to teleport from one grid to another. Grid operators that choose to block hypergrid access are deliberately confining their registered users to their grid whereas those who allow free access are granting both registered and none-registered users access.
We don't generally know or care how many pages a web site has until we start to use it and we may or may not know too much about a particular grid. It might be very small and weak running on a PC with home connection, or it might be a fully developed world with many connecting regions either hosted by the grid operator or connected by individuals as is the case with OSgrid. But just having a connection to the web is all it takes to make a world visible regardless of it's size.
The point is that the Metaverse is made up of multiple platforms we commonly call grids and most people understand what that is and, in my view, only those people with a vested interest in singing the praises of one grid over another - their own has the most traffic, most regions, has the most advanced code, etc, etc - will want to distance their grid from the smaller one's. But, collectively, the smaller grids represent the larger portion of the Metaverse which can only keep growing. Close worlds like Second Life are dead end streets and doomed to failure at some point in the future.
An open Metaverse will continue to grow like the Internet did. And an Opensim grid is a "Grid" because they all look and feel the same.