The first installer that came out sounds like a real carpet butcher and not a carpet installer. The president of the installation company that came out may have been part correct stating that the carpet can be restretched and e may be correct in saying the seam repaired. The second installer was correct in stating the furniture needs to be taken out of the room and he also may be correct in saying the back will come off. If it were me I would allow them to attempt a correction by reseaming and restretching with all furniture out of the room. I would want it it writing from the installation company that the installation will be performed to the manufactures standards or the CRI standards. I would also insist on a letter from them in advance that stated that if the correction failed they would replace the carpet at their expense and that it would be installed based on CRI or manufacturers standards. That is what I would want, how you handle it is up to you. Good luck!!
In response to public and governmental concern, WHO established the International Electromagnetic Fields (EMF) Project in 1996 to assess the scientific evidence of possible adverse health effects from electromagnetic fields. WHO will conduct a formal risk assessment of all studied health outcomes from radiofrequency fields exposure by 2016. In addition, and as noted above, the International Agency for Research on Cancer (IARC), a WHO specialized agency, has reviewed the carcinogenic potential of radiofrequency fields, as from mobile phones in May 2011.