That opinion is worthy, though it differs from mine. I see what happened -- if it happened as Comey suggests -- as clearly obstruction of justice.
So, you are the boss of the man conducting an investigation. You have power to fire him. You ask him if he wants to remain on as head of the FBI, then you say you need and expect his loyalty.
Veiled threat? It is barely veiled, if at all. The message is clear: You don't touch me with this investigation, or you're fired.
To all those who feel differently, your opinion is fine with me. I see the reasoning behind it. But that makes me no less vehement in my opinion. With me, it is clearly obstruction of justice. You don't use your power as president to block an investigation against yourself.