To understand Zen is to understand that a fairly strict set of precepts and standards are integral to its practice.
"Understand Zen" is an oxymoron. Probably that's why you are confused by morals. Zen is not something you should follow by action, it's something that you can't leave, so yes, morals are no concern in Zen.
I'm not trying to be critical, but the above is the kind of thinking that infused Zen once it hit the US and the hippie culture, beat poets, and the guru culture in this country after the 1960's. I do not believe that this idea that "Zen is something not understandable; morals are no concern in Zen" expresses a lack of understanding of the history of Zen, the teachings of the Indic and Chinese patriarchs.
I'm completely OK if people want to see Zen as something that is ungraspable, something that has no ethical anchor points....it's just not Zen, and it might be best if this kind of view was called something other than Zen. Maybe "American Beat Buddhism," though even that would be a perversion, in that there's nothing Buddhist about holding a view that there are no moral roadmaps or precepts in the practice.
"Dōgen tirelessly admonishes his disciples to practice unceasingly and strive further and further toward an unending moral and spiritual excellence. In Dōgen's view, a rigorous adherence to the precepts is descriptive of the moral character of the advanced Zen practitioner." Credit: Who is Arguing about the Cat? Moral Action and Enlightenment according to Dōgen By Douglas K. Mikkelson