Just so we're clear, the UK DoT has removed restrictions where specific airports and airlines have implemented the required additional security measures.
What you seem to be implying is that BA has made a decision not to implement the recommendations of the UK DoT because it does not believe it is safe to do so (i.e. nothing to do with the fact that BA is not prepared to pay the additional costs associated with the requirements).
I'm sorry, but it just doesn't add up. I appreciate BA does have to make regular tough decisions about flight routings and related safety, etc. But to imply that BA is better positioned to make decisions on security risks at airports compared to the DoT (which will be advised by the UK national security and international intelligence services) seems a bit far-fetched.
Having used both TK and BA this also does not make a lot of sense either, as BA have to spend money on staff at the gate, checking every bag for electronic devices. TK have more staff for this but also more passengers to check. They also have more scanners. Unless BA won't invest in the scanners?