I also find it interesting that you used the phrase "morally good form of serving a country", focusing on the country, rather than focusing on the people
Every doctor treats people. Cuban doctors in particular treat people in Cuba, so they're serving an entire country's worth of people. I don't see the issue with this description.
Medical doctors, generally speaking, care for people locally
If I commute 45 minutes to work I'm no longer caring for people locally, most patients seen by doctors are people they don't know or have heard about, all that many Cuban doctors know about most patients is that they're in Cuba and they're sick, so they get treatment.
I already explained the moral difference to me between a Cuban doctor choosing to move to Germany and make 5000€/month treating Germans, vs a Cuban doctor staying and Cuba and earning 500€/month treating Cubans (I'm making up the figures). I don't need hypotheticals about outpatient clinics, or rehab centres, or Netanyahu, I'm describing a specific existing situation and judging its morality, I don't see the need for imaginary alternative universes where the ICC works to explain how "doctor chooses to get a huge pay cut and treat people from their country" is, I believe, almost universally morally positive.