It's not as if he wrote down a gate address, TJ, it's just a sketch of a gate! Along with some math! Nothing anyone can use to get anywhere.

"It's like our version of your secret basement," he adds, since he's distantly aware of Torchwood's HQ. "Only more sterile looking, and with uniform regulations."

Which... Torchwood didn't seem to have? Maybe a dress-code he supposes, but no uniform.