If that's your unpacking, it is different from Mark's, which is "my definition of slavery is being forced to do something against your best interest". From such a divergent starting point it is unlikely that conversation will serve any useful purpose.

To answer Mark's actual points we will further need to unpack "force" and "interest".

Mark observes - rightly I think - that the program of "Friendly AI" consists of creating an artificial agent whose goal structure would be given by humans, and which goal structure would be subordinated to the satisfaction of human preferences. The word "slavery" serves as a boo light to paint this program as wrongheaded.

The salient point seems to be that not all agents with a given goal structure are also agents of which it can be said that they have interests. A thermostat can be said to have a goal - align a perceived temperature with a reference (or target) temperature - but it cannot be said to have interests. A thermostat is "forced" to aim for the given temperature whether it likes it or not, but since it has no likes or dislikes to be considered we do not see any moral issue in building a thermostat.

The underying intuition Mark appeals to is that anything smart enough to be called an AI must also be "like us" in other ways - among others, must experience self-awareness, must feel emotions in response to seeing its plans advanced or obstructed, and must be the kind of being that can be said to have interests.

So Mark's point as I understand it comes down to: "the Friendly AI program consists of creating an agent much like us, which would therefore have interests of its own, which we would normally feel compelled to respect, except that we would impose on this agent an artificial goal structure subservient to the goals of human beings".

There is a contradiction there if you accept the intuition that AIs are necessarily persons.

...but desires primarily to calculate digits of pi? ...but desires primarily to paint waterlilies? ...but desires primarily to randomly reassign its primary desire every year and a day? ...but accidentally desires primarily to serve humans?

I'm having difficulty determining which part of this scenario you think has ethical relevance. ETA: Also, I'm not clear if you are dividing all acts into ethical vs. unethical, or if you are allowing a category "not unethical".

Only if you give it the opportunity to meet its desires. Although one concern might be that with many such perfect servants around, if they looked like normal humans, people might get used to ordering human-looking creatures around, and stop caring about each other's desires. I don't think this is a problem with an FAI though.