Dear Lord. Pedant,Sir,
Your correspondent who signs himself as "Strummer", is surely mistaken.
A Glazier is not a member of the profession of glassmakers.
The noun is applied to a person who fits glass into windows and doors.
A maker of glass, typically an industrial chemist, is referred to as a glassmaker.
Yours faithfully etc...
You are of course, correct; surely it should be written „the profession of one who replaces glass“.
A retraction will be posted in tomorrow‘s Guardian, and the offending sub-editor has been taken outside and shot.
We remain,
Your humble servants, etc.