Both were excellent options. There was also the option of the Doctor inside of Jack, mouth around Jack, stroking him---wow, those were quite a few vivid images the Doctor wasn't aware his imagination could come up with. Jack was a bad influence on him. And, really, the Doctor couldn't care. He loved this.

But! He had to make a choice. Not really fair, putting all of the work to Jack, was it? He opted for the first of Jack's choices, and to follow with the second of his own.

He did as instructed, tethering their connection, wrapping strands of psychic energy like long fishing knots to keep them close. He could feel how much that meant to Jack, and it was good. It felt important to the Doctor, too.