In the grand scheme of things, this isn't a very big deal? Actual "space" flight requires many multiples of this speed. And isn't the main goal of Virgin Galactic to ferry tourists into space?
Think of how you attack a complex problem - you can't solve everything at once, but you try to break it into smaller ones. If you build a complex piece of software, you try various concepts on a proof level, then rewrite them until you have something workable, then integrate that to your big software. If you are smart, you also use libraries that were first started for projects that did something totally different but had to create libraries on the side.
Same here too. In my opinion, hybrid rockets will not be relevant for cheap space launch in the long term, but commercial construction and operations of carrier airdrop, the shuttle cock re-entry and gliding return are something that probably will be fine tuned a lot by Virgin Galactic (operator) and The Spaceship Company (builder).
They have picked a path with a high dry mass penalty (glider wings) and quite a lot of complication (a whole extra aircraft) but they certainly are in a very exclusive club, having flown safely to 100 km, twice, with a human pilot. Their approach makes sense for an airplane company. A rocket company would build a normal liquid rocket engine that could do it from the ground and come back and land vertically again.
