Context, Context, Context
Look at the Mar A Lago raid case thrown out as being unconstitutional.
Look at the lawfare against Trump.
Look at two Impeachments of Trump to remove him from office, one that took place after Trump had already left office.
Look at three years of the Mueller investigation.
This assassination attempt is in the context of republic ending lawfare and in the context of the election turning into a sweep of all the states in the polls.
You have billionaires and super pacs screaming to replace Biden and Biden acting confident that they will win and then gives the word to put Trump into the bulls eye.
This is the context. You can't separate out the assassination attempt from all these other attacks. In that context anyone working on his security detail would be on the highest alert.
This guy was climbing on the roof, in plain sight, spotted by multiple witnesses screaming to the police and watched by the Security snipers for 40 seconds. Plenty of time to send a word to get Trump out of there.
Based on the context and everything that happened the simplest explanation was a palace coup. Especially when you understand the influence Biden has on his security detail.