Welcome to TFP!!
Sorry it took a while for your welcome, but to be honest after I retired I don't see 5:24 very often
I think your logic is well founded. You already have identified the major problem, his self-proclaimed "Old School" attitude. Many people in the pool industry keep doing what they have always done, even though things change.
Yes, the VS and 2 speed pumps have been around long enough that there is stability in their reliability. Now, with that being said, will you have a problem if you buy one - maybe. Being mechanical devices some are going to fail. As you look at reviews, most people with problems and negative thoughts make their voices heard while happy customers tend to go about their lives without commenting.
Now, the key question is - Do you need a added expense of a VS pump? My gut feeling is probably not. When it comes to pools people tend to get too large a pump (I'm guessing your 2HP is overkill), too small a filter and run the pump too many hours. Unless your area has very high electric rates the payback time on the VS is probably going to be long.
A little more information might be helpful, such as how often do you use the hot tub portion, how often do you swim, do you have a pool cleaner to deal with (pump speed) and just for future reference, do you have a screen enclosure over your pool like most in Florida have (add the screen enclosure & pool cleaner to your signature if you have them).
Understand, you have fallen with a group of renegades who tend to buck "traditional" pool industry advice in favor of what we know works.