Usually it is the work of the one claiming something to prove it. So if you believe that AI does "think" you are expected to show me that it really does. Claiming it "thinks - prove otherwise" is just bad form and also opens the discussion up for moving the goalposts just as you did with your brain emulation statement. Or you could just not accept any argument made or circumvent it by stating the one trying to disprove your assertion got the definition wrong. There are countless ways to start a bad faith argument using this methodology, hence: Define property -> prove property.

Conversely, if the one asserting something doesn't want to define it there is no useful conversation to be had. (as in: AI doesn't think - I won't tell you what I mean by think)

PS: Asking someone to falsify their own assertion doesn't seem a good strategy here.

PPS: Even if everything about the human brain can be emulated, that does not constitute progress for your argument, since now you'd have to assert that AI emulates the human brain perfectly before it is complete. There is no direct connection between "This AI does not think" to "The human brain can be fully emulated". Also the difference between "does not" and "can not" is big enough here that mangling them together is inappropriate.