+ For instance saying it "has no tracks" but then ... it's in a tube. This seems to be nitpicking, as the tube is effectively a track. The question of whether something uses a track or not is mainly of interest because things that don't use tracks have more flexibility, and can go off-route. Something that requires a fixed guideway (like a tube) is for all intents and purposes, on a track.
+ Most importantly, the tubes would considerably safer than traditional high speed rail, since debris or other obstacles couldn’t get in and block the vehicles.
Er, is "debris and obstacles" an actual safety problem on existing HSR lines? Oh wait, Shinkansen: perfect safety record over 50+ years of very intense operation.
It's pretty clear that grade separation, and some effort to avoid trespassers, are important, but these things are of course standard practice. Putting everything in a tunnel would appear to at best offer a minimal safety improvement, at great additional cost.
+ Similarly, the vague hand-wavy discussion saying that the tubes would be "cheap and easy to construct" seem a bit specious. Either precision is required or not (and at 500+mph, one had better get this right!), and the form of a tube doesn't seem to make much difference compared to other maglev technologies, e.g. the "U-channel" being used by the JR maglev (one of the notable attributes of the JR tech is that it has a very large gap size, and so is less susceptible to precision issues, as compared to e.g. the transrapid tech).
So if you take existing JR maglev tech, and ... add a roof, is it actually any different than the vague "tube" notion this article talks about?
Maybe Musk does have some truly transformative idea, but certainly nothing in this article is that.
[I think Musk's coyness about this is pretty annoying... if he really has a great idea, and intends to make it public, why not just say it instead of making flirty glances and beating around the bush?]