Sephiroth not only isn't strong enough to control a huge mako rush, at that point it would probably destroy his mind. We just watched him go homicidal crazy, his mind isn't strong. Cloud would be in a much better mind state, and he needed Tifa to bring him back, all Seph had was Jenova, he certainly had nothing to cling to from his prior life.
Sephiroth's strength and mind state are both direct results of Hojo and Jenova. He had absolutely no descision in it. He cannot be held responsible for his actions even if Jenova wasn't in control.
There is no reason the knowledge of the Temple and Meteor, and the powers and appearances of Bizzaro and Safer were not from Jenova. Given noone else gains these powers, changes or knowledge it seems very far fetched that a crazy person who should be recovering from five years in mako mysteriously developes them. Espescially given the thing that sets him apart the most is the amount of exposure to Jenova he has.
The clones are controlled, people don't just travel to craters at random. Yes your hand does heal, but if it's cut off it wont get up and walk over to your wrist.
If Jenova can't absorb lifestream there's no reason Sephiroth should be able to, Cloud can't and the only difference is Jenova.
I choose logic over the words of crazy game characters when it comes to evidence.
