Open Source = no liability
Ah, the anti-Open Source crowd have crawled out from beneath their little stones to spout their misinformation! (The inability to spell "hobbyist", and its use as a perjorative, is a good clue. It is well known that anything motivated primarily by external reward tends to be done to a lower standard than something similar done primarily for the love of doing it.)
Source Code is the absolute best way of telling a (knowledgeable) user *exactly* what a program does, warts and all; because Source Code *is* the program, just presented in a more human-friendly form. If a program can cause something to happen, then a thorough examination of the Source Code will reveal under exactly what circumstances it can happen.
To put it quite simply, if a program is doing anything other than *exactly* what the Source Code says it should do, then it must be the fault of the compiler / interpreter or the computer itself.
Open Source authors, therefore, absolutely will *not* be held liable for anything that happens as a consequence of people running code they have written. Because as long as the user has been given the opportunity to examine the Source Code, and warned to assess its suitability for a particular purpose before proceeding, if they went ahead and did so anyway then whatever happens next is their own responsibility. If you are in full possession of the facts, then you cannot plead ignorance.
Authors of freeware -- software which is distrubuted gratis but as binary executables only -- would, however, be in exactly the position that you describe. And shed them no tears; if they are giving away binary executables gratis, they would have nothing to lose by giving away the Source Code as well.
The enormous disservice done to users by keeping Source Code secret from them would cease to be economically viable in a good many cases: many would find it cheaper simply to supply users with the Source Code and an exhortation not to copy it -- withholding the Source Code has done precisely nothing to prevent unauthorised copying of Microsoft Windows and Office -- than to insure themselves against the potential liability associated with concealing the Source Code.
And to answer lglethal's point, nothing that a piece of software does is particularly "special" and just because a program took you a long time to write, doesn't mean it's worth anything. Keeping secrets is a sign that you have little confidence in your own abilities. I do not believe that people would have due cause to say nasty things about the code that I write; therefore, I am quite prepared to show it to them. I would stand to gain precisely nothing by concealing it anyway; because what any program is supposed to do is evident, and somebody else could always write their own program to do the same thing (and, of course, they would then have the Source Code, and so be in position to ruin me by distributing that. Given a choice between two programs which perform identical functions, one supplied with Source Code is obviously more desirable than one supplied without Source Code).