Assuming scenario B occurs to the same extent as scenario A (I don't believe it has... yet.), there is no difference. This type of attack seems plausible, but are there reasons it would not be feasible/likely? However, should it occur, is there a defense against this attack that does not rely on miners making a financial sacrifice? I'm afraid that defense will not be sufficient.
Discussion
Giving individual miners the ability to construct their own block templates will go a long way.
This is the goal of Stratum V2.