Are posts in trash can counted toward activity?
Based on the quoted post below, the answer is NO. Removed or trashed posts affects users activity as well as your rank.
Can activity or my rank decrease?
Yes. It can only decrease if you have all the posts you made from a particular period deleted or the threads you posted in trashcanned. If you do it's possible to drop rank until you have enough activity again.
It should be 0 post, 0 activity.
Again, posts moved to trashcan is still counts. That's why you see 1 post on that profile and 0 activity.