Ridley is constantly asked, so he has to open his mouth. 
Plus Ridley has a relationship with the Alien property itself. With three films under his belt including the one that started it all, Ridley has become the fatherly George Lucas of the Alien franchise of sorts. So I'm not surprised when Ridley is interviewed, that someone will bring up Alien again, again, and again.
Maybe 20th & Ridley have left open the possibility of more Alien talks down the road?...
Sorry to be negative, but it’s all in the hands of Disney now.
The comparison with George Lucas works at a surface level. Disney no longer wants either George’s or Ridley’s input.
Eventually there will be an Alien reboot but it won’t involve Scott and the reboot will have nothing to do with the David storyline. That is done.
I think your opinion is being presented with too many absolutes my friend!
. I have placed bets myself on what is / what will happen using industry trends and reasoning, but unless we sit in on their discussions, neither of us know truly what will or won't happen, what is done and what isn't.
I do suspect Ridley may be in some sort of advisory producer man-behind-the-curtain role at the least, considering his recent statement that more Alien is in process, but going directly back to the Prometheus/Covenant route is doubtful. But we shall see!
