I have also (independently) found the same NYT article about Steiner firing where I noted this detail:
"In another interview, with
Radio Continental, Steiner said he believed that Federer was going to win the Wimbledon title when he had two match points late in the fifth set of the final against Djokovic."
Up to that point I could agree with you that the sanction on Steiner was harsh, but now I don't think so. This interview revealed that Steiner not only violated the "no interview" ATP rules but he admitted that he was actually biased during the match by emotionally supporting one player on his very match at play! The admission of such blatant violation of impartiality is unheard of. ATP had no choice in this case, IMO. One cannot officiate if he cannot be impartial. If ATP allowed Steiner to officiate in the future, in any Fed match in particular, ATP would face serious criticism from everyone, especially Federer's opponent who could question the match to be invalid due to umpire's bias. The strict rules about impartiality are there for good reasons, and I agree it's better to sacrifice an otherwise good ump who made a mistake here, rather than relax the rules.