It’s his business and to respect it, ask first before taking pictures or prying open hoods.
He may have had past experience that shapes his perspective that you aren’t aware of. He may also know that if word gets out that he has old muscle engines in cars in his yard, that thieves will come.
Or maybe it’s something else he thinks might happen that you don’t realize.
Point is to talk, ask and respect whatever he decides is best for his business and his livelihood.
Just like you would want.
