That sounds like either clueless reporting or an attempt at blame shifting. The heating system of a building is not a typical DDoS target, and it's improbable that somebody living outside of that building had a take against the inhabitants, knew of the right IP(s) for that building, and the effect a DDoS would have. It's more plausible that the control system was designed so badly that exposing it to the Internet (an…
Sounds like exactly the sort of thing I'd have done in my youth (if I had had the skills) if I would've discovered lax security in my own building's systems and it pissed me off.
IOT companies don't tend to have bug bounties et al, and shutting off the heat to some buildings seems like a mostly harmless way to get some publicity for the issue.