Ask HN: Colleague Thrown in the Deep End

Recently a developer began working in the small team of 5 that I'm in. I discovered this week that he has been assigned a gargantuan task to perform within a very short period of time. I really can't understate the difficulty of this task, it requires rewriting around 10% of the 1000+ test suite. I'm talking about the sort of task that is arduous to me, even after a year of working on this codebase.

What's more, management recently gave him a grilling for his lack of progress on said giga task. This dev is competent, willing to learn but completely demoralised by the situation and worries about being fired... I've politely communicated publicly to management that their expectations are wildly unreasonable and praising the progress anonDev has made.

What more can I do to stand up for this individual so that this doesn't happen next sprint?