FMF-
Are you sure those are the only 2 options? I can think of at least a few more:
3: Comey was building a case about Trump interfering with an ongoing FBI investigation.
4: Comey was seeking to preserve the Russia Investigation and did not want to bias his agents.
5: Comey felt his words alone were not sufficient to bring charges against the President of the United States.
6: Comey was considering rolling a Obstruction of Justice charge in with the Russian Investigation.
. . .
I'm not really sure why people are trying to make an issue out of this. It's very common for law enforcement officials to hold off on pursuing smaller charges so as to not compromise larger investigations.
You don't pull over a drug trafficker for speeding when he's on his way to pick up a cocaine shipment. And the criminal saying, "well the officer knew I was speeding and didn't stop me" in no way gets him out of trouble for either speeding or drug trafficking.
But I do agree with you. It will be interesting to see what Comey has to say. I can't wait until he testifies!