To truly be an "obstructed seat" certain criteria has to be met. Those stairs-seats would not meet that.
However, that will be a huge problem if they allow people to go up and down the stairs at any time and loiter on the stairs for any period. I had Sabres seats the past few seasons where there was stairs and a landing. It is obnoxious people who just get up during action, stand there, have no clue where they are going, where their seats are, decide to take a bite of their food, stopping, mid stair climb, etc.
If the stairs are relatively clear when the game is live, then they shouldnt be too much of a problem.