That doesn't work for me (and I think it doesn't fit so well with how Rowling is referring to Snape's death scene as his redemption either. It implies there's a self-sacrifice involved, IMHO).

What you describe is precisely what Voldemort was meant to assume, because Snape played his role to the end and acted exactly as you'd expect a Death Eater about to be betrayed by Voldemort would do. Snape was a consumate expert at lying to Voldermort. To stay true to his mission to the end, Snape had to die without raising any suspicion in Voldemort. He couldn't escape either, let alone appear to sacrifice himself. All Snape could accomplish by his death was convince Voldemort he was now invulnerable to Harry as master of the elder wand, which among other things would mean he might finally relax the protection set around Nagini, a crucial point as Snape knew Harry couldn't face Voldemort before Nagini was killed (something Harry knew as well), or it would all be for nothing, back to square one and this time with a Voldemort who knew how to come back, and knew his horcrux(es) were in danger. When he was forced out of the castle and witnessed that Voldemort no longer let Nagini out of his sight - a big problem - Snape was probably thinking he would eventually be forced to kill Nagini himself while Voldermort's attention was on Harry. Who else could?

I don't really buy either that Snape was so obsessed with telling Harry he had to die, as the last horcrux. Dumbledore had already left Harry that final clue with the snitch and the deathly hallows quest, and Snape was too intelligent to have believed he could convince Harry of anything, as Harry would never have trusted him again (Dumbledore would never have planned things up so part of the plan rely on Snape giving Harry any crucial information. He knew Harry would never trust Snape ever again after Snape killed him). The only reason Harry believed Snape's memories is the fact Snape gave them to him right as he died. It wasn't because they were crucial information to finish Voldermort that he passed those memories to Harry, it was just the last desire of a dying man that Harry finally learned the truth (and they were also the real reason why Snape was so frustrated with Harry's attitude with occlumency, and why he put an end to it after Harry's indiscretion. His indiscretion could have made him find the truth, which would be open for Voldermort to find, ruining Snape's redemption, and it also meant Snape could not reveal himself as an ally to Harry before Voldermort, or as it turned out before himself, died.)