Well, it did take them 12 years after the purchase to shut it down.. Apart from that, it sounds like the standard acquihire. Salesforce bought Ruby/Java/etc experts to make their platform(s) more amenable to Ruby/Java/etc developers.
Salesforce bought Heroku more than a decade ago. Company strategies change.
Consider it was for "just" $212m as well – https://techcrunch.com/2010/12/08/breaking-salesforce-buys-h... – rather than the ridiculous valuations similar companies would have nowadays. I imagine Salesforce made a fantastic return on it even ignoring any remaining value.
We are not "sort of winding it down".
Well you've done a pretty good job convincing everyone that you do.
Good luck trying to get the tooth paste back into the tube.