I do exact same thing when I plant with Vagalion. You can plant and teleport around AS LONG AS YOU ARE TOUCHING THE GROUND and holding fire with bomb on the site. It's more or less utilizing our abilities and ripping game mechanics apart to avoid a guy walking in with his fancy shmancy lace.

Just wanted to say - it's pretty much same thing with spider-man in that situation just he is visible where a vaga is not.