Answers to your questions in order:
#1 That didn’t happen, so no more answer required
#2 The general consensus IS that it is a plane. The general consensus of people paid to appear as “experts” on the news to say it wasn’t a plane is that “it wasn’t a plane”.
Do you need an expert to come on the news and tell you the sky is blue?
#3 It was a plane. It took two days for the idiocy to spool up to a level that an official response to state something should be obvious to people who are oblivious was required. I don’t see that as unusual.
#4 I lend credence to the contrail science guy because he is right. Being right tends to increase ones credibility, while being wrong, like the “expert missileers” tends to decrease ones credibility. Being wrong and not correcting yourself decreases ones credibility further still.
Another falsehood. The Pentagon issued a statement the day after it happened.