Samuels compares it to Marxism as the nearest ideology. Clearly downright prohibiting land ownership is both authoritarian and left-wing. Heavily taxing land as to have [nearly] the same effect is a proxy for that, in particular because imposing such a large land tax suddenly is effectively capturing land value (from its owners).
Samuels' paper is otherwise fairly sympathetic to Georgism. Members of the movement are described as being more individualistic than Marxists were, which the paper says was probably a reason for the lack of success of the movement. But it's not clear [to me] whether there was any deeper "libertarian" aspect to Georgism, other than not being as communitarian (or revolutionary) as the Marxists were, due to the more limited scope of the Georgist proposal(s).
Finally, there was also a bit of religiously inspired aspect to Georgism, in the sense that it related to the Protestant work ethic by emphasizing work productivity. But this idea doesn't get developed much more in the paper. (The Catholic Church fiercely opposed Georgism, but mainly because the Church was a major land owner.)
Samuels' paper ends by noting that a number of economists proposed to Gorbachev to impose Georgism-style land tax on the land that was being privatized. This makes some sense because the capture aspect (the most objectionable part of Georgism) had been done by the Bolsheviks anyway... so the proposal was basically: now there's the time to start reaping the true benefits, in terms of the supposed enhanced work productivity that a substantial land tax presumably provides.
And since you insisted on that chart, if "Rucker" on that chart is actual Benjamin R. Tucker (I haven't heard of a well-known political economist called "Rucker") then you'd place Georgism close to where "Rucker" is, but nudged further to the right (i.e. slightly less leftist). In a reply to Samuels, Sullivan, then President of the Council of Georgist Organizations, says:
Tucker took Proudhon’s mutualist
anarchism, including his Bank of the People, into a characteristically
American direction, synthesizing European socialism with
frontier-style individual sovereignty. Similarly, George prefaced
Progress and Poverty with his own mission of synthesis: “. . . to unite
the truth perceived by the school of Smith and Ricardo to the truth
perceived by the schools of Proudhon and Lasalle; to show that
laissez faire (in its full true meaning) opens the way to a realization
of the noble dreams of socialism.” (p. xxx). In this, Tucker and
George, the Anarchist and the Single Taxer, were in agreement—their
respective positions can be seen as variations of libertarian socialism
or, to borrow a label from Peter Valentyne and Hillel Steiner, Left-
Tucker was a scathing critic, and George’s ideas and politics were
among his regular targets. When George reversed his position on the
Haymarket case in favor of the verdict, when nearly every other
reformer around the world came to the opposite conclusion, Tucker
branded George a “Traitor” to the working class. The furor over
Haymarket marked the first Red Scare in U.S. history. It also marked
a turning point for George (and set a pattern for later Georgists),
who from then on lost most of support he had had in the labor
I don't quite know what to make of George's take on the Haymarket in terms of libertarianism-authoritarianism axis. But clearly George didn't agree to violent-radical revolution. You can interpret it as more support for liberty as in rejection of violence, or as more authoritarian as in deference to authorities, which does go together with George's "static" view of natural law. In fact Sullivan has more say about this when he talks of George's rejection of Darwin's theory of evolution, pointing out that in contrast Marxists embraced and "extended" the notion for their own purposes, i.e. revolution.
And as final note, if you reduce George[ism] just to that single issue of land tax/property, then you get a larger region of uncertainty. To accurately place on any kind of (possibly multidimensional) political map, one needs enough discriminant information, like how to get from where we are to the Georgist ideal. I think that placing Georgism on the left (of the left-right axis) is hardly disputable though.