The word robota (and its derivatives) occurs in the Czech, Polish, Russian, and - as I recollect - Ukrainian languages (in Russian it transliterates as rabota) and has the same meaning in each: work; and robotnik means worker.
Thus a "uterobot" is a "womb-worker." That's straightforward enough. If it seems to have a negative connotation, it may be because we sense there's something wrong with the objectification, reification, "thingification" of babies and mothers, whose personal relationship with each other --- like the personal relationship of lovers --- ought not to be reduced to a laboratory procedure or a commercial transaction.
You may note that we don't speak Russian or Polish here. The problem with "uterobot" is that it straightforwardly and incorrectly compares "rent-a-womb" worker with robot or android.
Those practices are questionable as themselves without incorrect vilification which can only weaken one's argument.
Note that I am not commenting on arguments themselves, for or against. Just nitpicking semantics...