By this standard every single senator, congressman, government official or FBI agent who eve met with the Russia ambassador, et al, should excuse themselves from “the investigation”.
Since he already said in his nomination hearings that he would recuse himself from anything connected to Trump’s election, he had to recuse himself.
In fact this whole nothing story was probably put out today, not because of Trump’s great speech, but because today was the day Sessions planned to announce whether he would recuse himself on the Russian hacking story.