The Brits are a close ally but they are not Americans. We don't have a list of foreign governments that are allowed to be involved in our politics. Trumps son has a meeting with a Russian who claimed to have oppo information on Hillary, meeting comes to nothing and they move on, it is not even clear he knew she had time to Russian government. Borderline treason and seen as strong evidence that the Trump campaign colluded with Russians to illegally influence campaign. Logic seems to follow the gnome steal underwear profit philosophy.
Hillary and the DNC pay a man with direct ties to a foreign intelligence agency to find dirt on Trump and then that dirt is turned over to the FBI to help fuel an investigation of her opponent and that is OK. Logic follows the kindergarten it is only wrong when you do school of ethics.
It takes a deep and persisting amount of bias induced blindness to think it is OK to work with a foreign agent to influence an election as long as you like the person running and foreign power involved. You can argue that he wasn't actively working for MI6 but he was a known foreign agent was a very well known agent with deep ties into the British intelligence regardless of his current status. What you can't argue is that is was somehow OK for the left to bring an MI6 agent into the election process but not OK for Trump to meet one time with a person who may or may not have been connected to the Russian government.