Victor -
1) re: " I and everybody can see that sloppy and hasty merges made by person who performs dozens similar actions every day (see his "Recent Activity") ALWAYS brought me problems on over twenty profiles"
Nope. I looked at several and they all looked good? So not everybody sees whatever it is you think is there.
Choose three that display what you are talking about - provide the link to each of those 3 and I will look and let you know if I can see it there.
2) there is no such thing as "creators of Primary Profile" -- there are just Profiles, and when it is discovered that two of them are profiles of the same person, then they are supposed to be merged.
The person doing the merging does not control which is Primary. When you click to Compare the two that are a suggested Match, the one shown on the left is the one Geni's algorithm has chosen for Primary.
If the two really were the same person, then the merge is good.
The Data Conflict Resolution Screen was purposely created - I am sorry you hate the way Geni's programmers chose to have Geni work, but the problem here is not something Jeff did wrong.
3) re: 'user of GENI will decide to OFFER me the merger " -- the decision on Geni is now and has been that anyone can merge any two Public Profiles on the World Tree. One gets "Yes, merge this profile" NOT "Yes, request to merge..." if both Profiles are Public Profiles on the World Tree. Also if one is not, but you have edit access to it and the other is a Public Profile on the World Tree or if both are ones one has edit access to.
I do not know what you do to "offer the merge" but Geni long ago decided in all those situations I just listed that each Geni user could just decide for themself and merge. Sending a PM to check in might be nice, but certainly not required and very rarely done.
4) " believe I have the right to reject" -- Nope, not on Geni if the profiles really are of the same person. Except if someone created a duplicate of you - that you have final say about. Your wife, your child, your sibling -- if they are not a Geni user and are Private Profiles, then a Manager, someone in the Manager's Family Group or someone in the Max Family of the Profile has to approve it - but it does not have to be you.
If the Profile is Public, no permission is needed.
5) "Can you or other representative of GENI curators do the procedure of return to pevious state of affected profiles?" - no, nobody can.
Geni got unmerge worked out somewhat, but it has never been perfected. It is undoubtedly better to just use the Conflict Resolution Screen than to check every profile to see what if any errors unmerge introduced and then deal with those.