Oh, well...thats great! Gives an option for extra-special neutering that was not available when the wormholes got reinforcements themselves. I guess I just have not noticed the chance, since I rarely kill the posts.
Actually they (the WH guardposts) were always there and always were the source of "WH reinforcements". They used to be permacloaked.
Wormhole guard posts are no longer perma-cloaked, and now have a small, token attack like the passive guard posts. These can now be seen and attacked if you wish, although they have 400 million health, so in MOST cases that's a colossal waste of time. But in an event where you have a ton of firepower and the desire to clear a wormhole without clearing the planet, you can do so.
Having these visible also helps to reduce confusion about spawned guardians for things like turtles, where there are multiple wormhole guard posts instead of just one.