Why would ever an average shared hosting user wanted to have SSH? Note, if you ask such questions, then you really new to the subject, and without having a good system administrator you'd better not give SSH access to your customers. Directadmin by itself has no tools to control what an user do in a shell, but it offers Jailed shell, which could give you some protection
Many of us consider giving shell access to be unsafe for several reasons:
Shell access users can read a lot of files, including a list of all usernames on the system, and most configuration files (though not passwords in a properly configured system).
Shell access users can run many programs on your server and access daemons directly, to, for example, do things such as set up their own email programs to spam without email getting into your logs.
Whether you consider it safe or not is up to you. If people request shell access from us we sell them a VPS, and watch their traffic carefully.