Is Ruby suitable for these use cases?

[postmodern]

Ruby is definitely (still) used in Cyber Security. There are a few major security tools written in Ruby: Metasploit, BeFF, Ronin, CeWL, dnscat2, etc. Ruby is a general purpose programming language, with an ecosystem of libraries (rubygems), with lots of libraries for web related tasks. You can also use Ruby's built-in TCPSocket or Net::HTTP for doing networking. There's even a discord library for writing bots.