Khilafah/HT Questions 1 - Seeking rule as part of Talab an-Nusrah

Seeking rule as part of talab an-Nusrah

From Methodology of Hizb ut-Tahrir for Change, page 20 of the pdf (page 38 of the book):
Bani Kinda and Bani Amir ibn Sa'sa'ah demanded in return for their protection of the Prophet
the right of the government and leadership after the Prophet (saw) dies. This clearly indicates that they understood from his request for protection that he wanted to establish a government, a political entity, a system of ruling over them. This is the reason why they demanded that they should take control of the government after his death.
And further down the same page (i.e., page 20 of the pdf and page 38 to 39 of the book): Therefore, the party added seeking the Nusrah, to the actions which it carries, and it started to seek it from the people who are in a position to give it. The party has two objectives in seeking the Nusrah:

Firstly; to get protection for the party so as to enable it to carry the Da’wah safely.

Secondly; to reach the government, so as to establish the Khilafah and bring back the rule of Allah in life, the state, and society.

When speaking to shebab of the Hizb they said that the second objective of seeking nusrah is based on the response from Bani Kinda and Bani Amir ibn Sa'sa'ah to the Prophet (saw).

When the Prophet (saw) interacted with Bani Kinda, they said to him (saw):

“If you are victorious will you give us the Mulk (authority) after you (i.e. your passing)?” The Messenger of Allah صلىاللهعليه وسلم replied: “Verily, Allah is Al-Malik (King and ultimate possessor of authority) and he places it where He wishes”.

When the Prophet (saw) interacted with Bani Amir ibn Sa’sa’ah, they said to him (saw):

“By Allah, if I were to take this young man from Quraish I would devour the Arabs”. He then said: “What is your opinion if we were to give you a pledge (Bai’ah) upon your affair, then Allah makes you prevail over those who oppose you, would the affair (i.e. leadership) belong to us after you?”

Why do these narrations not equate to the Prophet (saw) seeking rule when approaching the tribes?