The Buddha surrendered the life force before he ate the last meal:

DN16:3.37.4: So today, just now at the Cāpāla tree shrine, mindful and aware, I surrendered the life force.”

Before the Buddha surrendered the life force, he gave Ananda a remarkable opportunity:

DN16:3.3.2: The Realized One has developed and cultivated the four bases of psychic power, made them a vehicle and a basis, kept them up, consolidated them, and properly implemented them. If he wished, the Realized One could live on for the eon or what’s left of the eon.”

However, once the life force was surrendered, that opportunity vanished:

DN16:3.40.8: If you had begged me, I would have refused you twice, but consented on the third time.
DN16:3.40.9: Therefore, Ānanda, the misdeed is yours alone, the mistake is yours alone.

Here, the pivotal event is surrendering the life force, not the meal. This may sound strange, but it is a fact that people tend to die on specific days (i.e., close to their birthday). Cancer cells don't really care about birthdays, so something else is involved. Let's just call it "the life force".

The pork of the last meal was indeed deadly:

DN16:4.19.3: I don’t see anyone in this world—with its gods, Māras, and Brahmās, this population with its ascetics and brahmins, its gods and humans—who could properly digest it except for the Realized One.”

But, the Buddha surrendered the life force before he ate the last meal:

DN16:3.37.4: So today, just now at the Cāpāla tree shrine, mindful and aware, I surrendered the life force.”

Notably, before the Buddha surrendered the life force, he gave Ananda a remarkable opportunity:

DN16:3.3.2: The Realized One has developed and cultivated the four bases of psychic power, made them a vehicle and a basis, kept them up, consolidated them, and properly implemented them. If he wished, the Realized One could live on for the eon or what’s left of the eon.”

However, once the life force was surrendered, that opportunity vanished:

DN16:3.40.8: If you had begged me, I would have refused you twice, but consented on the third time.
DN16:3.40.9: Therefore, Ānanda, the misdeed is yours alone, the mistake is yours alone.

Here, the pivotal event is surrendering the life force, not the meal. This may sound strange, but it is a fact that people tend to die on specific days (i.e., close to their birthday). Cancer cells don't really care about birthdays, so something else is involved. Let's just call it "the life force".

So, although the pork was deadly, the life force was surrendered before the meal.