[StormEye]

"Does this mean that he won't be able to
testify about the data on his phones?

Most likely he won't be testifying about anything.
Fair probably he is deceased.

However, he'll most certainly manage to vote
several times in the 2020 election next November.

[TChad]

Most likely he won't be testifying about anything.

That may not be necessary, if Durham received the phones directly from Mifsud, and took a deposition from him at the time.

But it would be nice.