The early part (he must have had help, he must have had training, etc.) is not very convincing at all.

It's already been revealed that the shooter was a regular shooter at ranges so there's your training. He's either not heard this or is discounting it for some reason.

Respectfully, I disagree with you. I watched an earlier discussion that Larry had with Ritter where Larry held the line as you describe, whilst Ritter has pushed the line that Larry holds now. It seems Larry has had further discussion since then with some people and has reluctantly come to conclusion that Crooks has had help, although no other shooters were involved.

In essence, Crooks would have killed Trump if he didn't make that sudden move. Hence Crooks has had enough training and can be considered proficient. Most of the other circumstantial evidence involves the planning. The roof location, the ladder and then there is the encrypted mobile phone with access to overseas calls etc. There was a mention of drone being used prior to rally as part of planning surveillance of the area (not sure about that).

Where the collusion aspect would come in is that the secret service original team was relieved and replaced by incompetent management that have had no track record in secret service, which apparently stinks to high heaven. So, like everybody, I am waiting for more findings.