Yep, but that's the only way the bit with "Dante is the oldest Space Marine" in GW's books adds up. If you'd count the ones in stasis or lost in the Warp for some time, I'm sure many others are way older than "just" 1,100 years even without Blood Angel geneseed (DreadBjorn for example), obviously exceeding the lifespan suggested by GW.
And in my opinion, the Primarchs are dead, but that's merely a matter of personal preference, in particular one's threshold in terms of (pseudo-) realism vs sheer epicness.
Though either way you are right -- time has no meaning in the Warp!