My son has been sick with a bad cold and bronchiolitis for a couple weeks and while he's been sick I've been rocking him to sleep which means any sleep training progress we had made is back to square one

The bigger problem now is that in those two weeks he also started crawling and has gotten very good at pulling up to stand. Now whenever I put him in the crib if he is not very deeply asleep, he will immediately turn over, crawl to the bars of the crib and stand up. It feels like letting him CIO while he's standing up is somehow worse or like it won't work and he won't figure out how to lay back down again and just scream—am I wrong? Should I just let him cry no matter what position he's in? How do I get back to being able to put him in his crib drowsy and have him be able to put himself to sleep?
Re: Did the sleep training window close?
My Ovulation Chart