Wasn't it because they saved his life?
Yes, there was an assassination attempt made on Shaka due to his interest in a white-man led adventure party. Henry Fynn, a surgeon, treated his wounds which turned into a relationship between an English trading company, Farewell Trading Company, and the Zulu king. Francis Farewell, Fynn and company grew close to the Zulu king. Through this, the Farewell Trading Company provided the Zulu’s with many remedies to their ailments, also the medical skills Fynn applied to the Zulu’s. This respected and trusted relationship ensured the Farewell Trading Company’s protection and kept the British as a non-threatening occupier. As things developed, the Zulu king granted the Farewell Trading Company land which was in return occupied by the British to establish trade between the empires. This is where the Zulu king became a threat to his own people, very Roman’ish and not very ancestry. We all know what happened then, but remember that this was only documented by the British colonists.
So, we know that the Ingonyama Trust recently laid claim on this land which includes the land, Port Natal, given by King Shaka. Their reasoning through Zulu custom is that land ownership can only be changed by conquest which invalidates the documented grant, signed (X-mark) by Shaka and Zulu witnesses, to the Farewell Trading Company and co.
Colonialism vs tribalism. As much as King Shaka Zulu is hailed as a Zulu success story by black people, many don’t see the picture the king had on colonialism, he was assassinated at the end. Dingaan was not an good leader, historically. Dingaan actually targeted the Farewell and Fynn party, and other white settlements.
Why this story, people shaped the mindset and this is a special story considering that King Shaka was an ethnic cleansing wrecking ball, yet he had a workable relationship with white colonists. But then again, they were colonists themselves.