Let's see how the Australian Open was treated in the ranking era.
1973
A : Category reserved for the Triple Crown events.
B : Assigned to the most prestigious events of the regular series. Prize money over $100K.
C : Assigned for tournaments paying out more than $75K but less than $100K.
D : Assigned for tournaments paying $50K with larger draws (64)
E : Assigned for tournaments paying $50K with smaller draws (32)
F : Assigned to all other countable tournaments, regularly paying at least $20K
Australian Open had $30K prize money, so it would have been a F category, but it received a bonus step for being a Slam (pointed as D)
1974
A : Category reserved for the Triple Crown events.
B : Assigned to the most prestigious events of the regular series. Prize money over $125K.
C : Assigned for tournaments paying out $100K
D : Assigned for tournaments paying out $75K
E : Assigned for tournaments paying $50K
F : Assigned to all other countable tournaments, paying out more than $25K.
Australian Open had $40K prize money, so it would have been a F category, but it received a bonus step for being a Slam (pointed as E)
1975
A : Category reserved for the Triple Crown events.
B : Assigned to the most prestigious events of the regular series. Prize money over $125K.
C : Assigned for tournaments paying out $100K
D : Assigned for tournaments paying out $75K
E : Assigned for tournaments paying $50K
F : Assigned to all other countable tournaments, paying out more than $25K.
Australian Open had $55K prize money, so it would have been a E category, but it received a bonus step for being a Slam (pointed as D)
1976
AA : Category reserved for the Triple Crown events.
A : Assigned to the most prestigious events of the regular series. Prize money over $150K.
B : Assigned for tournaments paying out $125K
C : Assigned for tournaments paying out $100K
D : Assigned for tournaments paying out $75K
E : Assigned for tournaments paying $50K
F : Assigned to all other countable tournaments, paying out more than $25K.
Australian Open had $65K prize money, so it would have been a E category, but it received a bonus step for being a Slam (pointed as D)
So, as you can see there is a top Category (the Majors) that doesn't follow the prize money divisions.
The Triple Crown events were among the richer of the circuit, but there were some richer ones (for example Las Vegas or Palm Springs) placed in a lower category.
In a very few words : Australian Open was treated as a regular tournament, just with a little bonus for being a Slam, but away from being a Major.
And there is no speculation: it is what happened.
Let's go down now, without rankings, but with many info.
1972
Out of WCT, out of Grand Prix, $8,800 total prize money, almost all Australian players (like the Aussie Champs of 1920s - 1930s !) the worst Slam of the Open Era, clearly not a Major.
1971
Great tournament, part of WCT circuit that literally saved the Aussie Open after a 1970 in deep red and no money in the pockets of the Australian Federation.
Not really Open (GP players could not play). I can close an eye on this one
1970
WCT/NTL players banned (so not really open and so almost all the best players missing), average prize money. Very difficult to close an eye.
1969
Average prize money, but medium/good field. It was the first Australian Open, so there was hype to play it even if some good players were missing.
My opinion : if Laver didn't clinch the Grand Slam, it would have been contested like 1970 edition.