Why would Ruby risk missing this brief, and potentially only, window of opportunity in order to Western Union one of his strippers $25, with literally a couple of minutes to spare?
What benefit did Ruby stand to gain by doing this 'job'?
He obviously knew there was absolutely no chance for him to get out of there and get away with the murder.
How could he think it is a wise business decision to essentially throw away and ruin his life?
A lot of people were shocked, outraged, and furious that their president was assassinated, especially those in their home town.
Many would have undoubtedly like to have killed Oswald but most would not have the means and guts to try it.
To do so would be an irrational emotional thing to do which is likely what motivated Ruby.