I on the contrary find it perfectly reasonable. Academic publishing has its own share of bullshit and I can well understand someone, specially a retired person, wanting to give up on that kind of prestige in order to save time and energy for actual science. For example, as far as I know, Grigori Perelman has not published the work that won him an offer of the Fields Medal in any journal.

It is clearly stated in the article that Thomas Royen just wanted to get published quickly, as he isn't an academic.

I sympathize, after getting my PhD I went into the private sector. I often have side projects that could turn into publications, but massaging something through the publications process is a part-time job itself, and there's definitely quite a bit of who-you-know that can muddy things up.