I think the coach more likely intends to use Ronaldo as alternative player when the club needs to make changes and find goals. It's challenging for Ronaldo to find a position in Ten Hag tactic.
You're right, that's the problem Ronaldo has to deal with now. I know Ronaldo is the best player, but maybe he's not the best at the moment, so I agree with his decline. The coach's tactics and strategies have a big impact on the performance of his players, but I don't know because I think Ronaldo has worked with many coaches for good performances both at Manchester United, Real Madrid and also Juventus.
In the last match of Manchester United vs Everton, Ten Hag did not prioritize Ronaldo to enter his main line-up but Ronaldo came as a substitute for Martial in the first 30 minutes of the match. Ronaldo managed to score a few minutes before the end of the first half, it became Ronaldo's 2nd goal in 11 Manchester United matches.