Good idea. Let's compare.
Last lap in 2007- 54.4 (Lagat ran 51-high)
Last lap in 2009- 56 (Bekele ran 54)
What are you expecting to see that looks ridiculous? Obviously he ran faster last laps when he was winning races. I see someone who got 2 seconds faster in the last 400. Yes, when you use hyperbole to describe the race, it does seem unlikely that Farah could ever beat anyone.
Last lap in Beijing. 52.6
Last lap in Moscow- 53.5
Last lap in London 52.9
Last lap in Daegu- 52.5
As for your second point, you're saying it's unprecedented for someone who wasn't winning races on the global level at 26 (Farah's age in 2009) to win races later in their career. We have to compare him to other people who are "unbeatable".
Most people who have recently dominated distance running reach their peak in their teens or early 20's. Bekele, Asbel Kiprop, Gebreselassie, Daniel Komen, Rudisha. Farah didn't do this, therefore he must not have done it by natural means.
Yes, Farah is older than people who achieved similar accomplishments. He is an outlier in that regard. You have to go back to Miruts Yifter to find an older winner of an Olympic 10k gold.
And then if I try to point out that Farah's improvement over time isn't proof of cheating, you will ask why other people around him didn't improve the way he did.
So I would have to give an explanation for why all of those runners didn't become Mo Farah.
The problem with your logic is that you want me to prove Mo's innocence by showing you other people who have done what Mo has done who aren't Mo. Well, Mo Farah is the only person to have won the 5k/10k double in three consecutive championships. He also isn't Gebreselassie or Bekele. He also is not any of the people who used to beat him. He's different than them.
You're demanding that something exceptional should also be normal at the same time. Exceptional things aren't normal. But you can't use their exceptional qualities as proof of wrongdoing. At the end of the day, I think people need to be willing to suspend their judgment and recognize the limitations of the integrity of the sport.
I'm not certain that Mo is completely clean, but I don't think there is irrefutable evidence based on his performances alone that he is dirty.