Q: What happens if Beam us up is played with the Teleporter in play, and someone has a being with a Creeper attached to it on the table?

…Does the player with the Teleporter get the Creeper as well?

A: The key point to understand is that what’s really happening on Beam Us Up, with or without the Teleporter in play, is that the Keeper AND Creeper are sucked up into one’s hand… and then the Creeper is rejected, since you can’t hold it in your hand, and it goes back down in front of you.

Once you think of the action as happening in that way, it’s clear how to arrive at the ruling: the player with the Teleporter gets the Creeper, since they theoretically sucked both cards up into their hand, and then their hand spat the Creeper out, as it were.

See: If someone plays Beam Us Up, and one player had a being with a Creeper attached…