That’s too weird for most audiences. Removing the X axis altogether seems more appropriate (while keeping the labels). Then the plot area is still “bottomless”

That’s too weird for most audiences. Removing the X axis altogether seems more appropriate (while keeping the labels). Then the plot area is still “bottomless” in a sense, but the labels are where people expect to see them. Having the axis on top implies that the values are negative. Like an ocean depth chart.