To me it is not complicated either, just baffling that it was done in the order suggested here. To me, common sense would dictate that the first search team (looking for the body of TB) waited to get a warrant to search the farm, and then once they got it, they should have searched all of it, or at least the one building on it.
It baffles me to think that numerous trained professionals, once they found TB's body might have dusted off their hands and said, 'Yup, we're all done here', and not continued to search for, say a murder weapon, or a place where evidence might have been tracked or hidden. It baffles me that at least one trained professional must have taken a look into at least the doorway of the barn and thought 'Nothing could be hidden here under all that hay in a murder investigation'. And they all walked away. And left it without so much as a crime scene tape to keep trespassers out if they intended to go back to it at some future date.
It baffles me to think that when it was announced that a second search (the first one for LB at that location)was being conducted at the same farm, that one professional didn't call up another professional and say something like, 'If you're looking for a body from a year ago, you might also want to look under some of that hay in the barn'. It baffles me that no one on that second search team also thought, 'I wonder if we should check out that abandoned looking barn while we're here searching for a body, I wonder if we can get a warrant for that?'
Lastly, it baffles me that when they did decide to search the barn on the third search, that they seemed to go into overkill, in my opinion. I agree with you that the barrels are likely just a guy thing, aviation or not, I've never met a guy who could resist a barrel or an old army footlocker. Personally, I don't think it's complicated, but I think that the first two searches did require them to look into the contents of the only building on the site with more than a cursory glance, and I think that their inability to do that is baffling, because even a cursory glance would tell them that any evidence could be hiding under all that hay, or that there could be further rooms to look into with who knows what in them.