was it the only company he got a quote with?

I'd get many quotes from all companies if I was looking, did it a couple years ago but we have multi car discounts, accident free discounts, and this fall if we add our home ins it will be another discount across the board for that.
plus long time with same company=some benefits too.

A lot of it is your agent too, do they work with you or just sign you up and no updates or policy reviews after that??

Our old agent retired {no reviews with her at all} and our new agent is really nice and helpful , met with her twice now and I'm quite impressed.
she actually ran the numbers to show how much more of a discount we would get if we add the home policy with them also.

But I don't know what to suggest saying to your dad.
sometimes when someone suggests things to me , I just say I'll check it out later and leave it at that.
And hope it doesn't come up again... if it does I usually say I forgot about it and will get to it later.
hopefully after a few of those they will get the clue that I'm not really interested.