I received an email back from the VP of the mall in which we had our ADA issue. They have reviewed their policies, and despite what I was told (but per ADA standards), they do allow medical walkers, wheelchairs, canes, and crutches in the play place. According to his email, their policy has been reinforced with all personnel.
Very good news! I wish that it hadn't happened at all, but I'm so thankful that I didn't have to escalate, and all it took was a discussion and an email. Matthew and I will be back there soon, with his walker. It is a very nice play place for the little ones and I'm happy that they will be inclusive of all families with special needs.
I am learning as we navigate Matthew's journey, and this experience taught me that I need to keep a copy of the ADA in my diaper bag for just such occasions. Lesson learned, and thankfully, issue resolved!