#3 Why did Nexus help Kane in burying The Undertaker?

Between trying to take over Monday Night Raw and helping their leader Wade Barrett become the WWE Champion, Nexus somehow found time to help Kane settle the long-running score with his brother.
The Undertaker was buried alive for the nth time and in the subsequent promos, The Nexus kept their motives close to their chest. We only got "things will soon become clear" from Barrett before the angle was dropped altogether and fans never got a decent explanation.
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Since the rookies hated anyone and everyone who was marginally related to WWE like John Cena, Edge or Justin Roberts, the only logical reason can be that they saw Undertaker as another big wrestling figure and hence took it on their own hands to end him once and for all.
This angle had so much potential and we could have seen an eerie alliance between Kane and Nexus, but it never happened. Nexus has been long disbanded and most of their members are not even with the company right now, so don't expect to get a reason from WWE's side any time in the future.