It's possible Tim's story in Zdarsky will stop after June. If the new suit is permanent, this change could be the reason why Tim has so much relevance at the end.
It wouldn't be impossible this change to be planned for some months. DC tend to measure popularity with the pre-orders, while Tim's solo sales were bad since issue 1.
I don't doubt Tim being Zdarsky's favorite Robin is a reason for Tim's appearance in Batman, but I think it's possible DC has other plans for this.