Good journalism (and any information sharing) is about delivering meaning, not just facts. Facts divorced of context tend to lack meaning to all but those that fully understand their context, because they're prone to misunderstanding.

It's completely appropriate to center a headline around the likely meaning of the phosphine discovery rather than the discovery itself, because almost nobody is an astrobiologist. The scientists who study this stuff are just as compelled by the question of life on other planets as a layperson, because its discovery would be extremely meaningful to us as a species.

The question is not whether headlines should be represented as facts or their meaning, its whether the meaning that is presented is supported by the facts. In this case, it seems warranted.