Inigo gives him a bit of an 'aw, that sucks' sort of expression when Senku says his world is devoid of magic. Not that magic is as prevalent in Inigo's world as it is in certain others he's now seen or heard about, but they do at least have some magic.

.. then again, they don't have magic that could create running water either.. probably.

"Then it's a good thing they have you around in your world, huh? At least you can make some stuff that's almost like magic. Because you are just that good at the whole science thing."