I got the following question: I was wondering, did Suzuki Roshi ever allow anyone to sit zazen in chairs?
Yes. It was rare back then. He said that if all one can do is lie down, then that's the best position for zazen. His close disciple Trudy Dixon had to lie down in the Tassajara zendo to do zazen. He even had her lie down next to him on the raised area. When Peter Schneider was head monk, he hurt his knee, he had to sit on the raised area with a leg hanging down. In the city there were occasional people who had to use chairs. In the new book of vignettes about Suzuki, Zen is Right Now we have, "Once Suzuki was asked what’s the difference between sitting zazen on the floor and in a chair and he said, "The only difference is the legs." [writing that from memory - not exact quote.] I have no trouble sitting lotus. I work sitting with my legs up, and sometimes I do zazen in a chair or couch sitting with legs down or one leg down. I'd say to be skeptical of any teaching that says you can't practice if there's some limitation that goes against the norm.