Not really, no. A variant of what you are asking for was semi-doable in earlier iterations of Geni, through a function dubbed "Friends" which granted us the powers of dishing out view/read only rights to people who did not necessarily have any connection at all to our own particular parts of the tree. Though, close family members is another story entirely and they have pretty much always had the right to edit along "their own" lines since, well, frankly it's their "stuff" too, right?
If you're able to establish and uphold a normal conversation with those you want to invite beforehand, you can always request them to respect your work up to date and also to practice caution while going about their own business in the tree. In that case, you will all experience the best parts of collaboration and the tree will benefit as long as everyone involved maintain enough curiosity to keep documenting and exploring.
Also, as long as the tree is still isolated — i.e. does not connect to http://www.geni.com/worldfamilytree — you should have no problem maintaining a solid integrity whith only a few people involved. The move from a traditional "static" tree to a more "dynamic" environment with many people/agendas/wants/needs involved is excruciatingly painful for some who might find that the experienced loss of control and possibly the lesser data integrity to be unbearable for their delicate psyche! :)
Just know that objectives tend to vary between personalities and over time — it's always good to be as disaster proof as possible through GEDCOM backups, etc: http://www.geni.com/gedcom — and you'll be fine, no matter who does what, how, why or when.
Back when I joined in 2007 we had the choice to set unclaimed Profiles we managed so Family could edit them, or so only we ourselves could edit them - family just read them. I figured if anyone I invited - or who was invited by them in turn - didn't in a responsible way, I would just stop letting them edit the profiles I had added.
Does anyone remember when this was eliminated (ie when you stopped being able to choose whether or not Family could edit the unclaimed profiles)?