Yes, geoengineering is constistent with iron fertilization, because it is a very positive way that technology can be used to combat global warming. Algae blooms are a good way to combat global warming, because they can have a big impact, even though they only inconvenience humans and human activity a little bit. They are a good thing.
If it has a scientific purpose to benefit the environment, then it should be done until someone can provide proof that it is indeed harmful. If there is a decline in phytoplankton, then I believe proper action should be taken to enhance the biological productivity which can benefit the marine life there.