Of course the hologram can not.
Its not meant to replace rookies, just have a target at the right time at the right place to maybe catch some bullets or draw some enemies out.
Of course a rookie is better in any aspect, except more expensive, limited by transport slots (as you surely don't wanna carry 10 rookies with you) and costs score/morale if killed...
I´d imagine hologram use to draw sniper shots (or other powerful attacks) or waste a few enemy shots/TU if you throw them closer to an enemy than your units are, so less shots are actually fired at them.
Just giving some tactical options.
Like e.g. you ran around a corner and there´s 3 guys standing and you can't retreat far enough. 1 hologram closer than your unit and it´ll eat some shots/TUs. Or maybe throw 2 or 3 if you can, maybe the enemy is stupid enough to blast each other with explosives...
(Then again if you could throw 3, just use real grenades...)
Or maybe eat a chrysalid attack. Or waste an alien MC. Or eat 1 cyberdisc or blaster shot... Or make an enemy with a heavy gun melee attack since range too close... I can imagine dozens of possible scenarios where a throwable dummy unit would be kinda useful.
Cannot guarantee all are valid or worth it though.
