PET is indeed tear resistant, this shouln't be a problem with most photo machines as they don't use the sprocket for film transport even roller transports use leaders that move on drive cogs so the film is untouched by the machine drives.
It is possible if they have a roller transport they are worried about the blades cutting the end of the film-not an issue if the blades are sharp.
Anyone with a dip and dunk should be happy to process as will deep tank handline process.