He is correct. It is possible to replace just the glass, but the glass and LCD are glued together on this model by optically clear adhesive. The screen has to be heated, and a wire run between the glass and LCD (being careful not to cut into the layers of the LCD, scratching or burning the LCD). You then have to bond the new glass to the LCD using UV glue, or a large amount of OCA.
It is a difficult and risky repair, and if something goes wrong, it is expensive since a whole new LCD screen needs to be purchased.