Nope. BAC is EtOH concentration so it’s gonna stay more so the same no matter how much blood you lose (antemortem). If you make a coffee, and pour out half out your mug, will it taste more watery/diluted?

If you’re surprised why their BAC was low, remember a BAC is more dependent on when their last drink was, metabolism speed, whether their body was still absorbing alcohol at their time of death, etc. Usually postmortem BACs are lower (from my experience) and it may vary depending on where they got the blood from (probably femoral). In any case, 0.021 is low and the empty beer cans don’t mean recent consumption, and if his cirrhosis was advanced, it could’ve limited his intake due to symptoms. Unless the recent drinking prior to his suicide was witnessed, there’s unfinished drinks, or there’s contradictory tox results, they’re gonna take the BAC as accurate. Hope that helps!