Truth is, this was answered by Matt Cutts a while ago but when we discovered Google was not crawling tabbed content and they confirmed not once but twice that tabbed or expandable content may not be indexed or may be discounted in the rankings - then the question arose again - on mobile.
I asked Google's John Mueller yesterday, based on an argument I had with a group of SEOs the previous Friday, if Google will also look at the mobile template to determine if content hidden on mobile templates would be discredited. You'd think Google would look at mobile templates for mobile rankings and desktop for desktop rankings but no. As we covered recently, many mobile ranking factors are solely based on the desktop site - not the mobile site - believe it or not.
The same is in this case. Content you hide in expandable tabs or blocks or are hidden away for readability on mobile, is perfectly fine. That is, as long as the desktop version isn't hiding that content.
Google's John Mueller said this in a Google+ hangout at 22 minutes and 43 seconds into the video when I asked him about this:
We are looking at the desktop version. That's the canonical version so if you have the connection between the two pages, if they're separate pages and we'd be looking at the desktop version and that someone would be using for indexing. So if it's visible on the desktop version and you're kind of holding it away, simplifying it on the mobile version, then that's absolutely fine.If we run across situations where we see that people are abusing this that they're kind of, I don't know, showing cartoons on the desktop side and showing adult content on the mobile site then that something where we might have to kinda we reconsider that and see what we are doing there.
But for the most part I don't see that make sense, that you'd kind of shows something significantly different on the mobile site but on a desktop site because that on the mobile site it would be kinda lost.
Forum discussion at Google+.
