Hypothetical Restraint

The Gemarah in Avodah Zara 24B discusses the argument if the story of Yisro happened after the Torah was given on Mt. Sinia or before. Tosfos asks how it can be possible that Yisro came to join the Jews after the Torah was given. We know that Yisro came with his daughter Tziporah who was Moshe's wife. There is also another Gemarah that states that Moshe deliberately did not have relations with his wife on his own volition. Tosfos asks how it can be possible for Moshe to not have relations with his wife when she wasn't even there? Tosfos answers that it was considered as if he held himself back from having relations because he would have if he had the opportunity.

Let's consider the flip side of this supposition. What if someone would not restrain theirself if they had the opportunity, would that be considered as if they did the act. Obviousely we would say that a positive act is judged more favorably than a negative one in the heavenly court. However, in light of this Tosfos's reasoning the point must still be seriousely considered.