Some things presumably will be fixed during the editing process (including typos). His phrasing does suggest the 283 K maximum temperature for liquid water holds for all the locations cited when, according to the Haberle model, that should only be at the deepest parts of the Hellas basin.
However, the idea that large portions of Mars could theoretically be sites where liquid water could be stable for some time of the day comes directly from the paper of Haberle et.al.:

Title: On the possibility of liquid water on present-day Mars
Authors: Haberle, Robert M.; McKay, Christopher P.; Schaeffer, James; Cabrol, Nathalie A.; Grin, Edmon A.; Zent, Aaron P.; Quinn, Richard
Publication: Journal of Geophysical Research, Volume 106, Issue E10, p. 23317-23326 (JGR Homepage)
Publication Date: 10/2001
Abstract
Using a validated general circulation model, we determine where and for how long the surface pressure and surface temperature on Mars meet the minimum requirements for the existence of liquid water in the present climate system: pressures and temperatures above the triple point of water but below the boiling point. We find that for pure liquid water, there are five ``favorable'' regions where these requirements are satisfied: between 0° and 30°N in the plains of Amazonis, Arabia, and Elysium; and in the Southern Hemisphere impact basins of Hellas and Argyre. The combined area of these regions represents 29% of the planet's surface area. In the Amazonis region these requirements are satisfied for a total integrated time of 37 sols each Martian year. In the Hellas basin the number of degree days above zero is 70, which is well above those experienced in the dry valley lake region of Antarctica. These regions are remarkably well correlated with the location of Amazonian paleolakes mapped by Cabrol and Grin [2000] but are poorly correlated with the seepage gullies found by Malin and Edgett [2000]. In both instances, obliquity variations may play a role. For brine solutions the favorable regions expand and could potentially include most of the planet for highly concentrated solutions. Whether liquid water ever forms in these regions depends on the availability of ice and heat and on the evaporation rate. The latter is poorly understood for low-pressure CO2 environments but is likely to be so high that melting occurs rarely, if at all. However, even rare events of liquid water formation would be significant since they would dominate the chemistry of the soil and would have biological implications as well. It is therefore worth reassessing the potential for liquid water formation on present day Mars, particularly in light of recent Mars Global Surveyor observations.
http://adsabs.harvard.edu/abs/2001JGR...10623317H

Note also that these are possible places if there was water at those sites. There would not have to be geochemical evidence of aqueous alteration if there were no water, in any phase, present at the surface to begin with. But note that those orbiter measurements you mentioned are showing large deposits of sulfates on Mars and other aqueous minerals.
Additionally, there are still some differences of opinion by Mars scientists about what are the necessary conditions on the water vapor pressure for liquid water to persist as opposed to the total atmospheric pressure. The paper by Haberle et.al. clearly state it is the total atmospheric pressure that has to be above 6.1 mbars, not the water vapor pressure.

BTW, I have my own doubts about the 12 mbar maximum pressure number frequently cited for Mars even for the lowest parts of the Hellas basin from which you derive a 283 K (10 C) maximum temperature for liquid water. The maximum pressure at the Viking 2 landing site was already 10.8 mbars, and the Hellas basin is more than 4 kilometers lower than the Viking 2 site. It doesn't seem reasonable to me that the deepest part of the Hellas basin would result in only a 1 mbar higher pressure.
I once wrote Haberle about this and his response was that according to the global cliimate models (GCM) the maximum pressure in Hellas does not occur in southern Summer, when that large mass of polar CO2 ice melts increasing the atmospheric CO2 content, but rather in northern Summer. Possibly, but I would like to see some independent measurements confirming this idea.

Bob Clark