That particular vac shop apparently decided they couldn't make any money on it. Around here, vac shops get a lot of machines on an more or less free basis. (1) People bring them in for repairs and abandon them when given a quote for the work needed, (2) Sometimes vac shops will allow a modest trade-in value (say, $5 or $10) for such a used machine, just to clinch the sale. It usually is just another way to discount without actually backing down on the price; the shop often just tosses the machine, and (3) People will drop off unwanted machines at vac shops just to get rid of them.
Those T Series sell/sold new for $100 to $150 but I'm sure they've been sold for less than $100 on sale before. Like $89 at Walmart. So you take a machine that cost say $100 new and run it into the ground, from the standpoint of the vac shop, it takes too much in parts and labor to bring it back to a condition such that they can put it out for sale as a used machine. Their time is better spent trying to sell a new machine.
I've only worked on a few T-Series machines. I prefer to refurb earlier, made in North America machines. The T-Series doesn't seem to be as rebust as these, plus in my experience doesn't have as much suction.
I don't know how the current production system works for Hoover now that it's a Chinese-owned company. However, I suspect that many of the Hoover models made in China are sourced out to various Chinese manufacturers and they are made for, not by, Hoover, per se. I say this because the various Chinese-made Hoover models are made to different levels of inherent manufacturing quality.
So, you've got your free Hoover T-Series and you likely have plenty of time to work miracles on it, bring it back to serviceability, and don't have to worry about profit margins or overhead like a vac dealer would.