The balanced version
Pacemakers and induction: what the evidence says and why manuals still warn
A 2005 study set the safe distance at 50 centimeters. Later studies find the real-world risk low for modern devices. Manufacturers print the warning anyway. All three things are true.
Induction cookers generate a magnetic field at tens of kilohertz. A 2005 clinical study of implanted unipolar pacemakers near an induction oven concluded the safe distance was 50 centimeters or more. More recent testing of modern pacemakers and defibrillators against household induction hobs finds interference unlikely at normal distances.
What the manual says regardless
A commercial buffet induction range's manual tells pacemaker wearers to keep away from the plates, because the maker cannot verify every device on the market, and notes hearing aids may also malfunction.
Why a buffet is different from a kitchen
In a kitchen, the cook chooses to stand there. On a buffet line, the public stands at the equipment for as long as it takes to fill a plate, and nobody knows who has a device.
The neutral conclusion
The risk is probably small. The warning is real. A cordless heating cell has no field, which is a simpler thing to explain to a guest.