Thats just a quibble. If you have the tech to drag a 1km or so diameter asteroid into geostationary orbit, then you have the tech to set up reactionless drives (see recent NASA tests of the EM drive) powered by nukes or solar panels.
“If you have the tech to drag a 1km or so diameter asteroid into geostationary orbit...”
Well, we don’t.
“see recent NASA tests of the EM drive”
Verrrry preliminary tests, mind you. Ping me when there’s a spacecraft flying around powered by a reactionless drive. Until then it’s vaporware.