DD's dad was the same, insisted the diagnostic process was wrong, there was nothing wrong with dd, she just needed to grow up and toughen up. First letter from the Paed detailing developmental history, he said "They've only written down everything you've told them"
He was no support after SPD dx, his parenting style was to shout. Apparently yelling at a kid with 2nd centile hand praxis will enable them to eat tidily. I stopped having family mealtimes around the table and the OT recommended Caring Cutlery so both improved the situation.
DD hated answering questions, he would never ask open questions, (despite me telling him to every day) just say Did you do that because of X and she would agree with anything he said just so he'd stop. Even when his suggestion was utter rubbish she'd insist it was true, so he'd leave her alone.
He would criticise her for doing things that were part of her disability, I'd even go and get a report and show him the section which outlined why she couldn't do whatever it was he was criticising her for and he'd argue it was all a load of rubbish. All she ever needed to do in his eyes was grow up and try harder.
In an attempt to shock him into realising his behaviour was way out of line, when she was 8, I rented a house near her school for 6 months so she could have a nicer home atmosphere. It did improve things.
Dd had many more assessments over the years and it gradually dawned on me from answering so many questions that he also had ASD but he wouldn't entertain the idea. I got us all to do the AQ test, DD and I discussed our results, he hadn't done it yet, couldn't see the point of doing it, wasn't interested so I sent him the link again and asked him to do it and he continued to fudge saying he'd lost it and had forgotten what the score was and it was meaningless.
There's an awful lot on the support for partners with Asperger's thread that's very familiar to me too, in hindsight.
DD is adult now and in those days, there weren't any parenting classes available and there was nothing like the amount of info online like there is now.
There have been a few threads on here about unsupportive dads and what seemed to work for some of them was someone they would listen to like the GP or a Paed/Ed Psych explaining their child's condition to them. Some 'got it' after parenting classes. Maybe try those approaches? 