This has been an issue for ages. The booster being blocked by a/some alien teammates, keeping poison out of reach for other aliens. This problem has been compounded if a teammate goes afk with a large alien on the booster, it has also been a source of griefing.
We have just implemented a solution, now any alien that is boosted, can boost other aliens that touch said boosted alien. The boosted time for such a newly boosted alien would start out with the remaining time left from the touched boosted alien.