1) Begin by asking yourself whether it would be better for the person to have kept the money/assets. Be explicit about this. Do not engage in motte and bailey-style arguments in which this is implicit but denied.
2) Avoid suggesting alternatives not available to the individual. It may be preferable to have higher taxes and, consequently, fewer private charitable contributions. This argument is important, but orthogonal to any specific charitable contribution. If you believe there is mutual exclusivity between a given charitable contribution and some broader goal, be explicit. If you wish to engage in ideal world theorizing, be explicit.
3) If there are incidental benefits to the person, such as a tax deduction or public relations benefits, ask seriously whether those benefits are really a motivating cause. (For example, you might note that for every dollar you donate to charity, you cannot get more than a dollar in tax deductions, and that the direct cost is much greater than the tax benefit. You might note what substantial wealth could buy in PR if applied directly, rather than donated away.)
4) Ask serious questions about where the money will flow. Charitable Alternative B may be better than Charitable Alternative C, but try to remember Alternative A is keeping the money (see 1 above). If you are advocating for charitable donations, but of a particular kind, be explicit. Do not confuse such arguments with arguments against charitable contributions in toto.
5) Ask serious questions about how the money was made, but try to avoid “fruit of a poisoned tree” arguments. The eradication of polio is not an outcome that is tainted by Microsoft’s breach of EU competition law. If you want to criticize someone for being rich, do so directly rather than by criticizing them for giving away their riches.
6) Do not get hung up on legal structures. LLCs and 501(c)s have distinct costs and benefits, but neither structure completely determines how money will be applied. Nor are such structures immutable. At best, entity types may be tentative clues as to future plans.
7) It is possible to find psychological or philosophical reasons to believe that all altruism is self-interested. If you are a thoroughgoing skeptic of this kind, be explicit and do not selectively apply those arguments.
TL;DR – do not do what this author did.