We'd need a clearer picture of the SCL's structure in relation to what's going on adjacent to Arlington Station and utilities beneath Arlington, Boylston, and Providence Streets. It doesn't make any sense to me that it is 'impossible' to save the outer walls without 'great expense' given the easy access to the site from Providence Street for a variety of construction options.
It boggles my mind that Druker didn't make a big to-do about saving the historic SCL building facade to win over the public and then get away with proposing something larger on the back of the block that maxed out existing zoning or required a variance. I'm assuming he knew that project would get rubber stamped fairly quickly and didn't didn't think it would be necessary to make a fairly easy public relations concession.