As others have mentioned usually fuel is problem !! Water,dirt,algae or air usually the culprit ?? If original bought filters at Kubota dealer they would have record of it !!!The guy may be 100% legit. It could be just extremely bad luck. The probability is it is something else, but there is a possibility that it did just break when you got it home and calling a person a conman without proof can provide legal challenges along the lines of defamation of character.
I wish you the best of luck and will be interesting to see what the final resolution is.
Long story short bought a 2019 L4701 from an individual with 94 hrs . I test drove it for about 10 min everything seemed fine. Get it delivered to my house and drove it 200 yards and it starts acting up. Let it sit sounds like crap. Run it to dealer hr later who says he thinks it might need a new engine. Oil was sparkly. Regular warranty is out but stil 4 years on power train. With 94hrs I would hope kabota takes care of it. Dealer says they send off samples etc. Will know in 2-3 weeks. Any recourse?