As Boeing say there are 4 reliable indications:
- attitude
- N1
- groundspeed
- radio altimeter.
If I have a suspected Airspeed Unreliable why would you do anything except maintain standard takeoff pitch - 15 degrees - and maybe tweak power back to MCT, sit fat dumb and happy until MSA THEN start screwing around with things?
You can do anything you want - as long as you can justify it.
To me achieving MSA then doing the Airspeed Unreliable checklist increases the safety of the aircraft, that's what I'd explain to those lined up against me at the enquiry - just remember the warm and fuzzy feelings Sully and the F/O received! - for them to chew on.
Ultimately the passengers are safe, the aircraft's secure on the ground and I've written/am writing the report(s)....what's your problem??
Cheers.