#2. To set McIntyre up for a future face turn
Drew McIntyre has been pushed big as a heel on the RAW brand, but it's highly possible that the plans in the future don't call for McIntyre to be a long-term heel. Given his alliance with Shane McMahon, it only makes sense that they turn on each other or implode at some point of time.
McIntyre would be the biggest benefactor out of that and it's very unlikely that coming out of it, Shane McMahon will be the face. Given how hated Shane McMahon has become, fans will only want to see McIntyre turn on him more by the week.
It's not something that will happen soon, however. It's something that WWE might play up and build over the course of the next few months. Beating The Undertaker is just the start of it.