Christ, you sounds like somebody who is butt hurt because they took a 3 week course for a technical certification and are insecure about how "expert" they are compared to people with actual education. Their description is accurate enough for marketing materials. By your own admission there is at least one green wavelength that blood cells absorb and at least one red one that they reflect. Therefore their information isn't incorrect and anyone with actual expertise in this area (like myself and others with this expertise have pointed out to you) can easily understand how they could make a sensor based on this phenomenon. It's not a new idea. These sensors have been around for decades and are used in hospitals routinely. It's basically a modified pulse oximeter, just since it uses only one wavelength instead of two it gets only the plethismograph information instead of the pleth AND oximetetry. Which is enough to determine a pulse rate.