I would be more sympathetic if they'd said "do not take this patch and put it into production, it's almost certainly incomplete and buggy". "without careful review" suggests that they actually expected some possibility of it being complete and correct, at which point having somebody verify that currently it is neither is still really rather useful.

It's more an 'exemplar of concept' or something, really - which is still valuable, but I do wish they'd made that more clear.