I dare to say that most Trump supporters know that what he proposes is not exactly true but more the like of short-lived guiding fictions. But it is to regret that anti-Trumpists here and over there find literal interpretations to be easier to criticize and they make a riot about them. The consequence being Trump supporters not able to express themselves freely here even in a thread that invite them to do so....
I think you make an unwarranted assumption about the bulk of Trump supporters, who when asked do mention the literal policies quite often, apart from the general 'good feel' of white backlash.
That Trump's rhetoric may or may not refer to real action plans, some other set of actions of similar or compatible nature are reasonable to expect, insofar as there is actual policy being expressed; therefore, today's statements taken literally are valid surrogates for those policies and actions Trump is likely to attempt in the future.
As for safe spaces for proffering opinions without blow-back, I think the idea gravely mistaken. One should be able to offer cogent reasons for any given position; if they exist, some headway in shaping opinion can be made, if they do not, such policies and opinions ought to be properly debunked on a site such as ISF, and dismissed.
Finally, statements and rhetoric alone are quite enough to shape world opinion and affect international affairs. Trump is a candidate for office in a superpower with nukes and the world's largest military, a UN Security Council member, signatory to multiple treaties of its own earlier design, and a member of several alliances. Given that, loose rhetoric "a la Peron" isn't limited in its impact to the quaint tragic-comedy of Argentinian political dysfunction; rather, it affects the entire globe. A candidate for this office quite rightly should be taken to task for actions and words that are fairly indicative of his/her leadership attributes, or the lack thereof.