This is a reasonable position. I'm with you. I'm waiting for some independent reporters and investigators to run some of this stuff down.
Is the story that the board had an extra undocumented chip, or that the chip was used to exfiltrate data?
1 pin for GND, 1 pin for CLK and 1 pin for data.
Where is VCC coming from? Via pull-up resistors connected to the data line and capacitance.
I’ve seen MCUs run without direct VCC connections under these circumstances.
Either that or the chip is connected to VCC and a PCB ground plane on the other side of the chip.
Edit: boards are often sandwiched between VCC and GND layers. One could have a functioning device with just a few obvious “pins”/“leads”.
If they had come out and said, this is what this chip does, this is how it interacts with the rest of the board, or it phones home to x.y.z or something, I'd be a lot more convinced. As it is, the technical evidence is a little light as are the sources. So I think I'll hold on conclusions until we get some more info about what they think the chip was doing.