I'm pretty sure 'dark matter' candidates do include cold baryonic matter, it's just that in large part it's been ruled out due to a lack of observations exactly

I'm pretty sure 'dark matter' candidates do include cold baryonic matter, it's just that in large part it's been ruled out due to a lack of observations exactly like the one reported here. The fact that we had not seen it, until now, did not definitely exclude it from the definition of dark matter; it just made it rather unlikely. In the absence of observational evidence, alternative, more exotic theories were developed. The interesting question is how did this cloud form? One of the reasons, for example, that 'dark matter' can't be cold dead stars is that even if the stars were formed at the dawn of the universe, their remnants would still be warmer than the background temperature of the universe and thus we should be able to see them. Many other 'regular' baryonic sources were ruled out for similar arguments, eg, any process that could have created them would have imparted sufficient energy that we should be able to see it, or it would have been swept up into a star or formed a new star. The article did propose a mechanism, but I wish it went into it in more depth. Figuring out ways to explain the observation could lead to insights we had previously overlooked.