I don't know if you have this on your blogroll or not (unless you're Admiral Drax, who is my gateway to 'Guardsman-A-Day'). But this is unlike all of our other blogs.
This blog is, quite simply, art. In and of itself.
What you get is not necessarily a guardsman per se, but a slightly abstract window on one Astra Militarum deployment.
The regiment appear to have been not entirely standardised in the first place and appear to have been deployed and then forgotten about by the DM. The upshot of which is, as you browse the blog that bits are variously trying to remain staunchly Iggy, other bits are going feral and there's a hint that some of the farest flung bits might actually be turning into the enemy that they were sent to Litmus Prime to counter.
I suspect (and hope) that we are not going to get a definitive answer any time soon.
Some of the modelling and colourschemes might not be to everyone's taste or idea of what the IG aesthetic should be, but I think that this is part of this piece of art's engaging mechanism. As you browse through it, you never know quite what you'll see next (ie a model where every single component has come from a different kit), let alone what it might be.