I think so. To be safe, apply within 3 months, but technically, for a DTV, there should not be any issue not using it within the first 3 months. Other visa types do require activation within 3 months (except for multiple entry visas that are valid for 12 months or more, which operate the same way as a DTV).
Sounds like he may be that one Bangkok Post commentator obsessed with Covid, who's demanding Thailand reintroduce mask mandates because he's too afraid to live life normally.
I find the concept of an air border run much more stressful and less comfortable than a land border run, which you can do at your own pace. The only thing you have to be concerned about when going to a land border is what time the border closes...but unless you're pushing it, it's unlikely you would arrive so late that the border is about to close (although I have done that, most people wouldn't).
Bootlicking nonsense. Don't tell us what to do or what to feel. No, Thailand isn't "paradise". It's a nice enough country, but stop hyping things up. It is a country with real issues and foreigners will probably never be truly accepted here. Most of us know this.