David, the question is whose SEO?
Certainly not the florists who have been using florist.ftd.com/my_shop . The way FTD says they're handling this, florists direct links will disappear from search engines for weeks if not months - and FTD's error page won't tell the customers with bookmarks where to find the new URLs.
Somebody's getting optimized, but it ain't the florists - at least not for Easter, Sec'y Week & Mother's Day, the busiest 6 weeks of the year for most flower shops.
If the goal is long-term, then surely FTD could wait until June 1 (and let the shake out happen during a slow time) before destroying the current web presence of those florists.