The accounts are all linked together created on the same day (November 28, 2018) and their comments are separated by minutes without any identical reply (yet) that's to say they aren't bot but alt accounts operated by an individual created just for bumping the Bounty thread of GRABITY
Yes, you are right. It is probably the same user operating all three. All three accounts were created on
November 28, 2018, between 07:43:25 AM - 08:00:14 AM. Last time active,
Today between 02:53:16 AM - 03:00:13 AM. He logs into one account after the other, makes his posts and moves on. Its thread bumping and spamming.