Scher, by giving his opinion, is not risking his reputation at all.
However, IMO, if a person wants to express there position on an issue in this case to Von E. that is fine. Call him or send him a letter. I really have to ask why did this "Letter" find its way into the public's eye? It strongly appeares he wanted it to become public, not very professional, IMO.
Also, why did Scher & Hussain vote "Yes" to safety? Does not make sense to me!