From that Guardian article:
"I find the fact that they presumably spent taxpayer money to undertake such a hyper-partisan and unprofessional effort extremely troubling,” John Sipher, a former senior CIA officer said in an emailed comment. “There are normal ways to do this through our existing institutions, and their relationships with our British partners. This is bad on many levels."
"Republicans that are part of the House investigation should not be undertaking efforts without informing their Democratic colleagues," Sipher added. “Not only is it unprofessional but it is impolite. Mr Steele was a professional who worked on important and compatible issues with the US. He deserves better than being ambushed by a bunch of hacks."