Either I don't understand your suggestion, or you don't understand why the B-D extension is not palatable.
- The objection to the B-D extension is cost. A single stop, 5km+ subway extension is pegged at $3.5B or more. To add more stations to make it useful (i.e. McCowan/Eg, Lawrence, Sheppard), the cost would exceed $5B.
- The objection to the old SLRT proposal was that it continues to segregate Scarborough and maintains the forced transferat Kennedy Station.
From what I gather, you are proposing exactly what it currently being proposed - B-D extension along Eglinton to McCowan and then up McCowan to STC, with no intermediate stations. I don't think the route is 100% finalized, but the betting is this will be the recommended solution.