I'm surprised you haven't heard of the relationship between Alba Patera dn Hellas Basin. They are exactly opposite each other, as if a shock wave went through the core and created it. The same thing is with Argyre and Elysium Mons.
Nonetheless my point is made, no one knows this is exactly 3.6 billion years old, the times are known very poorly and may be off aby a factor of two. You can argue that this doesn't apply but I cannot accept any real certainty about events billions of years ago with no real evidence.
I'm sure many planetary scientists believe this but Queensland is the show me state unfortunately. I've read every single paper available online about Hellas before this, and there is no evidence I can see as to when it was formed. Crater counts are pointless. Hellas is a single event and need not have been related to any of them. Its timing could be completely independant of any statistical data there is because as they say single events make poor statistics.
The Noachian craters IIRC don't fall on Hellas directly, they are to the west and north.
The area may have been extensively modified in the middle Amazonian, so the age can be obscured:

“Channel and Lacustrine Deposits: Northwards of the proposed area of maximum glacial extent there is a region interpreted to be influenced by glacio-lacustrine processes. Kargel [5] mapped a portion of the shoreline of a possible proglacial lake. The MOLA data reveal that this mapped shoreline lies almost entirely at the -6000 m elevation level. Possible sources of input to this lake is water derived from retreating glaciers as well as outflow channels which empty to Hellas from the east. The esker field, in which the long axis of the features in oriented north-south, may represent subglacial flow of water into a proglacial lake. The eastern channels also might have contributed to this lake. These small channels resemble other outflow channels
in gross morphology, but are greatly reduced in size. Interestingly, channel cutting terminates abruptly on the basin floor in a manner that is very similar to the abrupt cessation of the circum-Chryse outflow channels. The paucity of tributaries along the length of these Hellas channels suggests a localized source region, possibly due to volcano/ground ice interactions.” Ibid. available online at http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6200.pdf
“Glacial Hypothesis: There are a variety of distinct landforms on Mars that have been attributed to the presence of ground ice/permafrost [7-9]. Today, although water ice is physically stable poleward of 45° N and S latitude, the only visible surface ice occurs at the permanent polar caps. Some investigators have suggested that the polar ice cover was once more extensive earlier in Mars’s history [e.g. 10-12]. Kargel and Strom [6] mapped the occurrence of a suite of landforms in Hellas which they believed share a common glacial origin. These features, which include glacial scour marks, moraines, drumlins, and eskers, are proglacial lacustrine deposits, are shown in Figure 1. The proposed age of the latest episode of glaciation is middle Amazonian. Three predictions of the glacial hypothesis that we have investigated with MOLA data are 1) glacial scouring on the south rim, 2) a shoreline from a pro-glacial lake in the north, and 3) a suite of glacial depositional landforms on the basin floor.” Bradley J. Thomson and James W. Head “HELLAS BASIN, MARS: EXAMINATION OF A GLACIAL HYPOTHEISIS WITH MOLA TOPOGRAPHY” 32-th Vernadsky-Brown Microsymposium

Hellas is the youngest looking of the major impacts, it is much less filled in than Argyre, Isidis, and Utopia. All of this simply means that the exact age is hard to determine, and the whole system of aging is innately inaccurate. We still have no idea what erosional processes occured over billions of years, indeed that's the point of White Mars. We can't just look at these things and say it happened on the 20th January 3.6 billion years ago. Why not an odd number, like 3,583,465,212 years ago? Because no one has a clue about the 100 million years, that why all the zeroes are in the number. There's just too many things unknown about Mars for me to take any of these Sagan like billions and billions as anything more than a guide meaning a really long time ago.