If it's compiled it will be safe, any other developer who sees your source code can see it of course, it depends how you feel about that. To the best of my knowledge decompiling VB6 is impossible.

For anonymous web stuff here we create a special account with no password expiry with read only access and code it like you do in a DLL. That is the accepted practise and how Microsoft did it in the Visual Interdev web development course we went on.