Here is the relevant section cited in that Wikipedia article from Visuddhimagga of Buddhaghosa that seem problematic for the view of mere cessation as the orthodoxy of Theravada:
DISCUSSION ON NIBBÁNA
[Question 1] Is Nibbána non-existent because it is unapprehendable, like the hare’s horn?
[Answer] That is not so, because it is apprehendable by the [right] means. For it is apprehendable [by some, namely, the nobles ones] by the [right] means, in other words, by the way that is appropriate to it, [the way of virtue, concentration, and understanding]; it is like the supramundane consciousness of others, [which is apprehendable only by certain of the Noble Ones] by means of knowledge of penetration of others’ minds. Therefore it should not be said that it is non-existent because unapprehendable; for it should not be said that what the foolish ordinary man does not apprehend is unapprehendable.
Again, it should not be said that Nibbána does not exist. Why not? Because it then follows that the way would be futile. [508] For if Nibbána were nonexistent, then it would follow that the right way, which includes the three aggregates beginning with virtue and is headed by right understanding, would be futile. And it is not futile because it does reach Nibbána.
[Q. 2] But futility of the way does not follow because what is reached is absence, [that is, absence of the five aggregates consequent upon the cutting off of the defilements].
[A.] That is not so. Because, though there is absence of past and future [aggregates], there is nevertheless no reaching of Nibbána [simply because of that].
[Q. 3] Then is the absence of present [aggregates] as well Nibbána?
[A.] That is not so. Because their absence is an impossibility, since if they are absent their non-presence follows. [Besides, if Nibbána were absence of present aggregates too,] that would entail the fault of excluding the arising of the Nibbána element with result of past clinging left, at the path moment, which has present aggregates as its support.
[Q. 4] Then will there be no fault if it is non-presence of defilements [that is Nibbána]?
[A.] That is not so. Because it would then follow that the noble path was meaningless. For if it were so, then, since defilements [can be] non-existent also before the moment of the noble path, it follows that the noble path would be meaningless. Consequently that is no reason; [it is unreasonable to say that Nibbána is unapprehendable, that it is non-existence, and so on].
[Q. 5] But is not Nibbána destruction, because of the passage beginning, “That, friend, which is the destruction of greed … [of hate … of delusion … is Nibbána]?” (S IV 251).
[A.] That is not so, because it would follow that Arahantship also was mere destruction. For that too is described in the [same] way beginning, “That, friend, which is the destruction of greed … of hate … of delusion … is Arahantship]” (S IV 252).
And what is more, the fallacy then follows that Nibbána would be temporary, etc.; for if it were so, it would follow that Nibbána would be temporary, have the characteristic of being formed, and be obtainable regardless of right effort; and precisely because of its having formed characteristics it would be included in the formed, and it would be burning with the fires of greed, etc., and because of
its burning it would follow that it was suffering.
[Q. 6] Is there no fallacy if Nibbána is that kind of destruction subsequent to which there is no more occurrence?
[A.] That is not so. Because there is no such kind of destruction. And even if there were, the aforesaid fallacies would not be avoided.
Also because it would follow that the noble path was Nibbána. For the noble path causes the destruction of defects, and that is why it is called “destruction”; and subsequent to that there is no more occurrence of the defects.
But it is because the kind of destruction called “cessation consisting in non-arising,” [that is, Nibbána,] serves figuratively speaking as decisive-support [for the path] that [Nibbána] is called “destruction” as a metaphor for it.
Which is part of his Vibhaṅga; the Abhidammic text on analysis. From what I can tell, he simply does not mention or focus on the death of an enlightened one as anything special. I dare say that focusing on what happens after the death of an enlightened one is treated by him as at best irrelevant to the path and at worst not conducive to actually practicing it. That seems in accordance with what I understand the Teacher to have taught.
But in anycase there’s an3.100 on the mutability of kamma for others reading along.