As a workaround:
Create a feature layer first using the Make NetCDF Feature Layer Geoprocessing tool in ArcGIS Pro, and then rasterize the created output. Specify latitude and longitude as Row Dimensions as well. Without row dimensions, the tool creates one point only using the 1st value of latitude and the 1st value of longitude.
I think your issue is, that the pixels are not square in the geotiff (Pixel Size = (0.061855670103093,-0.046487603305785)) and since I think you can't specify a geoTransform in Cesium, the png ends up distorted.
I don't know much about Cesium, but as far as I see it you have a few options:
Use gdal2tiles to build a Tile Map Service which you should be able ...