I bet your dad will end up a LADA - but if the endo is watching out for it, she should catch it in time. Yes the tests would probably show he was producing the antibodies - you might ask why he hasn’t been given them.
Your dad was just diagnosed - so was my 35 year old daughter - talk about feeling quilty (and I have 4 other children - hope she is the only one who gets it - she is the oldest)
My family has a long history of LADA type diabetes (long before it was recognized) - my great aunt got it at 30 (was one of the first people in Illinois to use insulin), my mom got it at age 40 (the first pills were just on the market so they tried those but she was soon on insulin). I got it at age 29 and my uncle (my mom’s brother - over 6 feet tall - very thin - walked 2-4 miles per day) got it at age 60 - he too ended up on insulin after a few years though he was of course diagnosed as a type 2. None of us were overweight when diagnosed (I gained weight on the pump - the joy of being able to eat more foods & still keep good control)