I don't know what policy the state of Maryland has about using the armory for public events. Any idea what the Maryland constitution has to say about forbidding it to groups based on the content of the ideas expressed? I know what the US Constitution has generally been read as saying on the matter.

National Guard Armories get used for all sorts of large assemblies, from square dances to pet shows. If the front person from the white supremacists presented him/herself as a common or garden variety concert promoter, the responsible person at the Maryland National Guard end might not have known what was going on until the point when everything hit the fan.

It is, of course, also possible that the responsible National Guard person was a secret sympathizer all along. Further investigation, and all that . . . .

Lots of "National Guard Armories" are commonly used as performance spaces for people who can't quite afford private concert venues. I dimly recall hearing free concerts advertised at the White Marsh Armory when I lived in DC (and I know I've heard others used that way), so I suspect it's one of those. (There's also the possibility that "National Guard Armory" is just a name, and it doesn't actually belong to the Guard any more...) The name is probably misleading in this case, suggesting that it's a restricted Guard-only space, when it's probably closer to being a cheap public exhibition space.

In which case, the question becomes roughly analogous to "Why are the Illinois Nazis allowed to parade through Skokie?"

(Put more formally, I checked with Kate, and she says that the issue isn't whether it's publically owned or not, it's whether the space is generally used for public performances and political speech. If it is, you can't deny access on political grounds, even to adherents of an especially loathsome political philosophy.)

It's not an exact parallel-- for one thing, it's probably easier to find an apolitical fig leaf to hang over denying a "Rock Against Israel" concert than it is a parade (Given the "only those who attended the rally were allowed entry" thing, you could probably argue that it wasn't really a public performance...), and I would've shed no tears had they been denied the chance to use a public facility for their carnival of bigotry. But there's something to be said for the principle that everyone, no matter how monstrously bigoted, gets the right to speak their mind.

I suspect that was the thinking of whoever approved the show-- that however much they might've liked to deny the Maryland Nazis use of their concert space, they were legally obliged to let them play. It might not be true, but that's probably what they were thinking.

"Battle of Seattle"? Puh-lease.