Ok, come with me for a moment.
Total or marked reduction in power, drop the collective. No brainier. Instinct to captain of this experience.
I get intermittent partial power loss (fuel pump problem? Low fuel - sucking alternat slugs of fuel/air?). Oh no, this can't be happening. But power comes back, so I pull for height - even if only to buy time if it deteriorates further. Power never fully restored, rotor rpm reducing fast. Boats burned.
I must emphasise that I know NOTHING. This is all pure pprune speculation, and those with deep type knowledge may be able to comment on possibility of such a partial/intermittent power loss scenario which, at v low level, urban, night, single crew, could suggest to a highly experienced captain that pull and hope looked a better bet than precautionary dump the collective and ar.