This question already has an answer here:
During Round 2, Phase 2 in the 2011 Tchaikovsky Piano Competition, the conductor Alexey Utkin used a pen to conduct for at least 2 Piano Concertos, such as for
Mr Seong-jin Cho's performance of Mozart's Piano Concerto No. 20 in D minor, K.466
and Ms Yeol Eum Son's performance of Mozart's Piano Concerto No. 21, K.467.
I know that conductors can choose to conduct with only the hands and no tool?
I ask not about musically immaterial or negligible reasons such as forgetting to bring a baton or the unfortunate possibility of being unable to afford one.