Does the Extraterrestrial Alliance pursue actively, humans doing astral travel to capture them in this way?

This is true and does happen. So there are many manipulations done to those during such excursions unless safety is in place. There can be a round-up and then a series of programming steps taken to undermine the person prior to their return so they come back damaged, they come back altered, and will henceforth be in service to the Extraterrestrial Alliance in some way by having been programmed to accept, believe in, and instrument the perspectives and desires of the Extraterrestrial Alliance. So the dark ones use every opportunity they can to leave their mark, to undermine humans and corrupt their world.