Its still lava, there were no cells in the input, so in a way, the centrifuge was making a cell from nothing(or much less actually crafting something instead of throwing out the contents)
Edit: i looked at the recipe recently and saw it was fixed, also saw there is a new slot for lava (Hmmm )
yeah, the sole reason of that slot is so that you can pump lava via bc pipes/TE conduits to it, and process 64 lava stills for tins and coppers.. same for the H2O slot in the Industrial Electrolyzer..