Nothing stops the big guns to take over by indirectly buying up...

Nothing stops the big guns to take over by indirectly buying up the shares and that is how most of the funds roll.
Without creating too many splashes they buy up shares and ensure a seat on the board eventually.
Because the big companies are under the control of these funds, as long as they can control the target company, they would not care?

We are still in the early stages, so not surprising that there is not solid, written interest yet, having said this, may be the company has already been approached informally which we are not aware of.
Companies won't make their intentions public until they are aware they would get majority of support otherwise a failed takeover will be a bad publicity for the purchaser.