Your assumption is unjustified TBH, because HN comment section is not representative of retro community. Now I also cannot understand how something can feel same as old historic device - this is not true even for differen gens of the same hardware. Say Apple-IIe feel substantially different from IIc and deeifferent generations of Sony PS 1 are also feel different.
In any case I would agree with title "100% new C64" if it were made from silicon level replica of chips, not FPGA's, much like new 6502 sold on aliexpress are generally good replicas of NMOS 6502, with the quirks and even current consumption faithfully reproduced, not some Xilinx Spartan-based simulacrum of the real thing.
That might be an argument if the only market was for projects like the linked one, which provide drop in replacement for period-accurate replicas, but the market is also full of full FPGA reimplementations and machines that adds all kinds of additional features, which shows there's a substantial portion of the retro community who don't care even about whether the result provides accurate reproductions.
This is not a market for retro, it is a market for replicas, an entirely different one. Still a replica is a replica, and should not be advertised as a brand new original machine, which the original title (before edit) was about.
In any case I would agree with title "100% new C64" if it were made from silicon level replica of chips, not FPGA's, much like new 6502 sold on aliexpress are generally good replicas of NMOS 6502, with the quirks and even current consumption faithfully reproduced, not some Xilinx Spartan-based simulacrum of the real thing.