Doesn't look like either black locust or honey locust to me....but that could be just me! Who told you it was 'locust' in the first place?
That would be me, exercising my foot-in-mouth know-it-all skills with which I am frequently wrong and overlook small details.
I can see that you are all right - it does not resemble any type of locust. I even looked at some Locust trees we have on campus and it's not even remotely similar. The closest thing I've found to it is Aralia spinosa, or "Devil's Walkingstick".
It was a pain (no pun intended) to pick up and get in the trunk. It ripped the bag of dog food you see in the picture, too. Dog didn't care, of course, since I left a nice trail for her to clean up when I brought it in.
Nearby, there were smaller diameter sections of it, which do look like the images I've seen online. I've just never seen a picture of one this thick. Weird wood. I wonder what its properties are?
I'll take some end grain pictures of both logs so I can provide more info for this. Thanks very much for all your suggestions and observations!