Meaning the defender is in position and the offensive player runs straight at/into the defender.
Is this a foul?
Is this a dangerous play?
Should the defender get out of the way and let the offensive player catch the disc uncontested to preserve safety for all?
Is it a foul? a dangerous play?
Possibly yes. It sounds close to dangerous play. From USA Ultimate rules, some examples could be:
- I. 1.
The following are non-exhaustive examples of dangerous play:
- significantly colliding with a mostly stationary opponent,
- running without looking, when there is a likelihood of other players occupying the space into which the player is traveling,
If these have occurred, it is both dangerous play and a foul.
should the defender get out of the way and let the offense catch the disc uncontested to preserve safety for all?
It is the responsibility of all players to avoid contact, so yes the defender should move if necessary to avoid contact. Doing so doesn't prevent them from calling dangerous play
- I. 1. a. 1.
The vast majority of dangerous play will involve contact between players. However, contact is not required for a player to invoke this rule where there is reasonable certainty that contact would have occurred had the player not taken steps to avoid contact. [[A player is not required to hold their position and receive contact in order to call “dangerous play,” but the mere possibility of contact is insufficient to justify a call. Furthermore, if the offending player stops or changes their path such that contact would not have occurred, contact was not “reasonably certain.”]]