1. At 75 years of age, he will not live to be 175
2. The law dictates that the punishment per murder must be 50 years
3. He's been convicted of two murders, and must have both charges applied to him unless we are not to expect punishment for one of the victims.
Ergo, he must have a term much longer than his lifespan.
There are a thousand details I just skipped over (concurrent sentances, multiple crimes commited in the same act, stacking versus non-stacking offenses, etc) but this isn't unusual and is a perfectly rational and sane outcome.
Judges are elected officials, so sometimes they like to make a nice big show of giving out a 1000 year sentence to appease the masses, when "life in prison without parole" would have done the same job.
I dunno if I buy the "dehumanizing" argument, but I certainly think it's unnecessarily confusing.