I guess my point wasn’t that it was somehow your fault, just that some of the responses seemed unfairly harsh on the dealer.
Had it really been rolled off the trailer that way, as was implied in the OP, and with parts missing, that would be, without a doubt, on the dealer. But it was obviously used some, and those sort of parts do sometimes rattle loose and become lost in use, especially when the machine is brand new- hence all the pre-use checks to look for loose bolts and such.
I’ve forgotten to pin my stabilizers before, but it made itself readily apparent as soon as I started to pull away and turn the wheel. If you made a couple passes back and forth with a bush hog, surely someone would have noticed it swaying around uncontrolled when you turned.
I’m betting they were there, but they came loose near the end of your shakedown run. If it was swaying around freely that whole time, someone would have noticed.