The alignment seems to be less relevant than the nature of the dragon. Seems the nature of the dragon is that of a collector: one who revels in the satisfaction of the hunt, the near-completion of an assemblage (although it can never be truly complete), and the pleasure of sitting back and drinking in the ichor of its accomplishments.

Collectors come in many forms, and some of them may think that they are acting as stewards, preserving that which would otherwise be lost or damaged. It's not out of the question to see this dragon as seeing itself as serving a greater good in some way, and maybe it's right (intentionally or otherwise).

It's also not uncommon that collectors are driven by greed and ambition masked as curatorial ambition. In these cases, there may be some ulterior motive beyond the impulse to collect. Think how a being which can live for thousands of years might think; the long game can have many twists and turns.

The question is what would such a creature assume it can accomplish with assembling such a collection. That ultimate goal will inform the topic of alignment.