I agree they were technically "dumping", but not in an intentional way to destroy any other company's business. Really, the Japanese pretty much had the market to themseleves at that time. I disagree that the tariffs had anything to do with Harley's resurrection. There was just very little potential overlap in potential customers at that time. What saved Harley was restructuring and a renewed commitment to quality and reliability, and their genius in marketing the "Bad boy" image to average people.
But that's just my opinion. It didn't really hurt the Japanese, and its biggest effect was that the US got 700cc versions of all the 750cc bikes the rest of the world got.
The potential for overlap of customers only had to be very small to cause some damage, if you recall the times. HD wasn't making and selling that many motorcycles. You are correct that it probably didn't hurt the Japanese much.
I also stated in an earlier post why I felt HD made the turn around so successful. It was similar to what you stated. So we agree there.
I wanted a good, dependable, heavy motorcycle for my own riding desires. When they finally made one - I bought it.
And it is still worth about the same as I paid for it new.