The man claimed that the posts were a joke, but police still plan to seek a full protection order, which, if approved, would keep guns out of his hands for a full year.
Police became aware of the posts last week when notified by the Seattle Police Department's Criminal Intelligence Unit. One post shows the man holding two AK-47-style firearms and pointing at the ceiling, with the caption, "one ticket for joker please."
Officials found other posts in which the man claimed to be an incel, which is short for involuntary celibate, and posts that illustrated a "history of violent and disturbing social media threats directed towards women," documents said.
"(The man's) threats of recent mass violence coupled with a history of prior threats to harm and kill women, demonstrate that (he) is a risk to public safety if he is allowed to continue to purchase, possess or access firearms," the ERPO petition read.
The man is expected to have a court hearing on Oct. 15.
The release of the movie "Joker" has prompted increased security at theaters across the country, with the FBI saying it has looked into posts made by extremists about the movie and warnings over potential shootings at movie screenings.