I think what you're missing is that Signal does not need to place any files on any phones for their purpose, and likely will not ever do so.
Their intention is to render using Cellebrite for court evidence worthless by suggesting that the record could have been tampered with at any point, if any phone the user scanned had Signal on it.
Proving that no phones ever had an 'aesthetic' file that could cause damage to Cellebrite is impossible, and they've provided clear reason why it is impossible to prove.
Their intention is to render using Cellebrite for court evidence worthless by suggesting that the record could have been tampered with at any point, if any phone the user scanned had Signal on it.
Proving that no phones ever had an 'aesthetic' file that could cause damage to Cellebrite is impossible, and they've provided clear reason why it is impossible to prove.