Is the intent behind "safeguarding against temptation" merely the absence of aroused lust, and is it permissible to attend coeducational studies while striving not to fall into prohibitions, despite not being safe from succumbing to lust?

There is no contradiction between the two statements mentioned. Looking at a non-mahram (definition) woman is forbidden when there is fear of temptation (fitna) or arousal of lust. The arousal of lust prevents intentionally looking at a non-mahram woman and at anything seen other than one's wife and bondswoman. Looking at a non-mahram woman is permissible on the condition that one does not fear temptation and does not intend pleasure. If one intends pleasure and fears temptation, then looking is absolutely forbidden. Looking with lust is absolutely forbidden for anything looked at other than one's wife and bondswoman. Whoever needs to study in mixed schools or universities must lower their gaze from non-mahram women and avoid everything that incites lust.