cmc unless you are operating in an obscure state of operation, what you have been told is utterly misinformed.
Your company SOP invariably over-rides any manufacturer publication. If your company SOP dictates a maximum of 55 degrees, you must abide by it. If Boeing subsequently update their procedures you must wait until your company updates your SOP accordingly before you accept Boeing's 70 degrees.
Manufacturer's methods only apply if there is no such guidance or rule offered by way of company SOP.
As I say if your governing authority promotes manufacturer's SOP as a priority over company SOP it would be a new one on me. Guidance on the sequence of referral to publications, and what takes priority, should be given in the introduction of your company Part B SOP (or its equivalent in your operation).
Furthermore, you should be able to find an absolute performance guarantee to prove 70 degrees is a safe assumed temperature. If you use third party published performance tables such as Flygprestanda, EAG etc. and 70 degrees doesn't appear in there, you would then have to spend considerable time extrapolating the performance from the Boeing Performance publication. Most perf tables I have used reach a maximum of 64 degrees.
There is a growing cancer among many Boeing 737 pilots I have met who proclaim "ah but Boeing says....." which is nonetheless a total contradiction to their company's SOP. There are many of my employer's SOPs which I don't particularly like, but are not unsafe, so I adhere to them without argument. If I felt so strongly that an SOP was unsafe only then would I go raise it with the Flight Safety department to ask for review. So far I have never had cause to do that.
You should ask your colleague who "blamed" you to leave the airline industry and go and get a job flying for Boeing.
