Fetal reduction in case of triplets is a controversial topic, as the risks of abortion due to the procedure as well as complications of having 1 dead fetus within the uterus are present. However, chances for complications due to multifetal pregnancy with twins are less than with triplets.
Susten is definitely indicated in your wife's case, and is being routinely used in similar cases without adverse effects on fetus.
You can request your own obstetrician who has advised fetal reduction for details of the procedure and related websites.