"Halt and Catch Fire" BIOS cloning scene unrealistic?
Yes it is reasonable. Been there, done that, on a smaller scale. Also duplicating ROMs by writing each address and data with switches. At the time, equipment to do this was all very expensive often part specific development systems from parts manufacturers or DataI/O or HP.

However, in '83 I would have used an AIM-65 running Forth and a little wire-wrap work, or an Apple II and BASIC or Forth and automated the process in a day. AIM-65 would also allow printing a listing and was 1/10 the cost of the Apple - and printers were also expensive.

AIM and Apple had audio tape mass storage and disk drives were again, very expensive. $3000 to $5000 was a lot of money then (about $400 for the AIM-65). Note that IMSAI 8080 owners hand entered the bios every time they powered up - until ROM boards came along with better bootstrap loaders.

Is the ROM soldered in and they didn't want to remove it? See the front panel of an IMSAI-8080 for an example of manual data and code entry.