Yes, you are missing something. But first I have to say that I'm impressed that you've put the photo back into the bin. That was utterly pointless, of course, but it never ever occurred to me to do that even just to see what might happen. So, good job.
Anyway, you're on the right track. The Bone Wagon is going to play a part in tracking down the florist, but right now Manny has no idea where to begin looking. He needs a trail to follow.
Next to the Bone Wagon there is a puddle of sproutella. One of the cans the florist was carrying cracked open when he landed. You have in your inventory a grinder with a skeletal arm in it. Bone sprouts in contact with sproutella. So, play around and see what happens.