The reason I suggested seperate abilities, is that it adds an element of uncertainty to playing this card. there is a turn delay between playing the card and being able to transfer it to the opponent through "invade". if the abilities are seperate, playing of TH followed by the opponent lobotomizing it, TH will have backfired. You will now be being poisoned instead of your opponent. with no way to transfer it over.
Under the current version, lobotomizing removes the poisoning effect, so it would be better to wait till your opponent transfers it to you side before you lobo it. Because you gain a weak attaker.
It is a matter of preference I think. My version gives more reward for quick control, but punishes you for not reacting fast enough. The current version gives you more leeway, but you wont be able to make TH backfire, other that gaining a little bit of damage from having the TH on your side as an attacker.