Cleon
Legend
I think the bit about spelljamming implies they let you breathe in vacuum, right? I did add the toxic bit as a bit of poetic license, but I'm willing to take that out. I could go either way on the bees, but I think general "attraction" may be too vague.
A spelljamming vessel carries a bubble of air with it when it leaves an atmosphere. Outside this atmospheric envelope will be either vacuum of phlogiston (depending on whether they're inside a Crystal Sphere or not). Any living creatures aboard will consume the air, eventually rendering it stale and then unbreathable.
So, I would interpret the text as meaning a skullcap ivy host does not consume the atmosphere in the ship's envelope (or, rather, the ivy replenishes the air as fast as its host consumes it). I can't see any support for it allowing the host to breath in vacuum.