This is an interesting point that you are making, and I agree that later in the scriptures, conditions were set concerning the possession of the described entity portion of the earth, first mentioned in Genesis 13:15. However, I am not sure that these conditions that you allude to can be found in the Book of Genesis. Perhaps you might like to enlighten me on the scripture passage where these conditions are mentioned, particularly the first mention of the conditions.
A condition IS Always Established ...
By an Offering...From One party To another party.
AND...
The Other Party ACCEPTING the Offering.
Example;
Any BANK can Offer you....a loan, credit card, savings account, checking account, pay your bills account....blah, blah ....IF you Accept their Offer...(whether or not you pay attention to the Banks “FINE PRINT” of the Banks TERMS) your Accepting...is your Agreement TO BE BOUND by the TERMS.
Any FAILURE of you TO abide by the Terms...will result in a NEGATIVE Consequence Upon you.
Okay...Scripturally...
Moses was A Head Of his Family, workers, their families, ie a clan of communal people living, working, tending animals and chores together.
Moses personally...chose to Subject Himself To the Authority OF God...Making God HIS MASTER.
Moses was NOT ONLY learning and doing the WILL OF his Master....
Moses “as the Head Of His Clan”... Moses had become...The teacher, the Spokesman, OF God, to teach, Be the example, for his Clan TO ALSO, understand ...To BE / Remain a part of Moses’ Clan...AS WELL....requires the Clan members To Willingly Submit to God Being THEIR MASTER.
Every man has Freewill. Choose to Submit, Be Subject To the Terms....or Not.
In Brief...
EX 19: 5
Gods OFFERING.....IF....THEN
EX. 19: 8
All peoples of Moses Clan Response...We will Do
For 4,000 and forward....for All the children of Israel......Each Established Tribe Of Israel....
The IF...Then....Offering Continues.
The....We will do....Continues.
And the negative Consequences....for Failing TO Do....has been Repeated Over and Over and Over for Generations.