Now, that said, I would not/did not personally choose to log time as an SIC in a part 135 or part 121 operation as PIC, even if I WAS the sole manipulator of the controls.
It's simply not considered "industry standard" when it comes to applying for jobs or sending resumes out. The only consideration that I might give is for insurance purposes where an insurer might require x number of PIC hours to be insured on a particular model aircraft. (This is much more of an issue in the part 91 world).
In short: Is it legal to log SIC time as PIC? Yes. Is it a generally accepted industry practice? No.