&. works like #try!, not #try.
And here is description of #try! (from documentation):
Same as #try, but will raise a NoMethodError exception if the receiving is not nil and does not implemented the tried method.
So basically it saves you from calling a method on nil, but if an object is presented it will try to call its method as usual.
The quote is from Rails Documentation, and so it’s important to emphasize
that Ruby does not provide #try; it’s provided by Rails, or more accurately ActiveSupport. The safe navigation operator (&.) however, is a language feature presented in Ruby 2.3.0.