I second the idea that it sort of sounds like he is losing senses, doesn't like it, and is coming to you for help and reassurance.
Also, canine dementia is a thing, where they can have trouble understanding things they used to and have trouble processing immediate experiences into memory. I'm not saying that is where your dog is, I'm saying it is something to be looked for and maybe ruled out.
I don't necessarily agree about penning him, if it will keep him out of the way of machinery, and he can still tell you are nearby and it is a comfortable spot. I'd say "where he can see you" but that seems to be part of the issue. Where he can hear you and it kind of smells like you, maybe padded with an old jacket?
I had an older cattledog with arthritis in his hips and knees, and he could no longer safely navigate stairs. He went from sleeping on the bed for a decade to sleeping on the couch with the stairs gated off, and seemed to be just as happy that when he was blocked off he did not feel guilty about not being able to climb the stairs anymore and could stay where he was. We ended up putting dogbeds in every room and carpet runners on all the slippery floors, just to make it easier on him. He adapted, and we adapted.
I'm not sure what to say about him suddenly wanting to be in your space beyond that, because my girl lab has always wanted to be in my space...laps are OK, but sleeping on my chest is even better, so I've never let her have run of the place while operating machinery. Plus, I am a worry wart and would hate to have anything happen to her. I'm not sure how much of that behavior is "lab", how much is "girl dog" and how much is just her.
I think a little time between the both of you figuring out a new way of dealing with movement in the yard and around the machines that works acceptable for you both would be well spent, and while there may not be anything that a vet can fix, sometimes just the knowing can help you both deal with what is going on.