Our prisons are designed for revenge and punishment not just to those going to prison, but to have a terrifying affect on others.
So ironically, the use of 5 years prison time is the real terrorism, in the literal sense of trying to make people terrified of protesting and of putting someone in a cage for 5 years.
5 years is also the maximum sentence for illegally selling firearms, violent disorder, performing female circumcision, assault, abandoning young children and some cases of sexually assaulting a child.
Basically the same as planning to block a road /s.