I don't know if this applies to all deleted answers (I didn't have time to check ;)), (see edit) but at least some of them don't show comments on the mobile website. As an example take this one (only visible to mods and high-rep users on CodeGolf.SE).
I believe these should be shown - even if it's not a common use case (apparently, because I couldn't find this bug being reported before), just because not showing content that actually exists sounds like a bug to me. (And I actually, I did notice it because I knew the answer had comments which I wanted to read.)
Edit: After ProgramFOX's comment, I had another look, and it seems that the comments are only missing if all of them are collapsed by default. On the same question as the above link, I can see the comments of all answers, where at least one comment has been upvoted (such that not all of them are collapsed).
To reproduce here on MSE:
- Go to this deleted answer (note the "show 1 more comment" in there)
- Click "mobile" link in footer
- No "show 1 more comment" thus no way to see the comment.