I am pretty sure they are alt, or they know each other somehow. Also, it's true the post doesn't deserve 25 merits as well. But unless there is clear evidence of merit abuse and merit sell, most probably he won't serve the tag. You may keep an eye on their activities. Because theymos isn't too strict during sending merits.
If a DT member tags you for something stupid involving merit (ie. probably anything less than selling merit), then they're not going to be a DT member for much longer.
Though it was about a merit source, he seems quite soft about sending merits. To be honest, I am too. I want more merit circulation in the forum. But don't encourage merit selling or abuse anyway. If there is clear evidence of merit abuse and selling them, I might tag them. As a merit source, I know that merit sources can't sell their merits. Otherwise, they could spread it anywhere they want. This means normal users are free to send their merits as they want, but can't abuse merit system anyway.