I kind of doubt that. Chris Sawyer is on record being really hostile to open source reimaginations, especially OpenTTD (and it's just a reimagination at this point as OpenTTD shares no assets or code with it's predecessor). It wouldn't remotely surprise me if Atari was putting legal pressure on the OpenTTD devs.
I don't think they'd have any case for legitimate legal pressure but clearly some kind of underhanded bullying. Hopefully no one buys this
I think really hostile is overstating it. He's clearly not a fan, but he seems content to (mostly privately) disapprove rather than take actions against it, which is what would to me qualify him as hostile.