Obviously he is going to use a pseudonym, especially as he still stands a chance of being employed by SQ group in the future. No point in burning bridges, is there?
Since you know so many people in SFC to know that there is nobody named James Tan, you would then also know that what the letter stated is the real situation for self sponsored pilots.
IMO, the letter was very restrained and well articulated. It did not attack any organisation and was just stating the facts as it applied to him. Kudos to him for not getting personal or vindictive in telling his side of the story. The ****-stirring came from the readers perspective of how they interpreted what he said.