Firstly, lets not damage the F/F at all, so do not impose large concussive compression loads into the head tube while hammering from North, South, Etc, and Etc...

Is the steel bolt still stuck inside of this alloy adapter?

If not stuck, perhaps the ID can be re-sized with a drill up to perhaps 3/4", then a slender (or slenderized at the grinding wheel) Sawzall blade inserted such that the upward limit of the blade's travel will not come up over the top edge of the steer tube.
A "Sawzall" blade will from my experience not start cutting into the steel steerer unless the working edge of the blade gets leaned over so as to contact the inside edge of the opening in the steerer, so from there, only one full/clear cut down to the steel surface inside of the steerer is needed to fully de-compress the extremely compacted layer of corrosion that otherwise still acts like a highly-compressed clutch pack (after the bond is broken by applying reversing twist and/or torch heat). The heat does wonders for stuck stems I've found, as the lengthwise expansion of the aluminum inside of the steel steerer forcibly breaks the bond (but still doesn't free the remaining, fierce "clutch" grip unless the slot is fully cut through the inserted stem, post, adapter or whatever.

I advise cutting gently enough so as not to have the blade digging into the aluminum with such resistive force so as to force the tip of the reciprocating blade above the top end of the steerer.

Alternately, I have freed regular quill stems using only the application of a "starting to smoke" level of torch heat to the quill, followed by cooling and application of penetrant from both ends as final cooling takes place. This, followed by applying an ice block to the quill for ten minutes allowed me to twist most of them out.

If using heavy twisting force, be sure to grip the fork crown (not the front wheel) to resist the twisting, I once broke a dropout free doing the latter (and you don't want to compromise the fork's alignment).