1/2: sojiro doesn't recognise akechi
YES. GOOD. THE BOY IS PRESENT WE BEGIN er
But let's have a look at slightly older Boy #2 here (Joker, of course, ties for Boy #1, while Morgana is a cat). Sojiro is being a bit weird in general here, and if you're like me, you might have missed it. Sojiro reacts to Akechi like a stranger: "oh, someone's ignored the closed sign and walked in..."
But Sojiro knows Akechi. He knows exactly what he did on 11/20, and before. He knows he worked for Shido. He knows he murdered Wakaba—Wakaba who, of course, is right there in Leblanc with them on 1/2.
I don't think Sojiro ever expresses an in-game opinion on Akechi after 11/20 (he certainly allows him back into Leblanc in January, so he may be deferring to Futaba like everyone else) but before the big November reveal, he likes him. He approves of him. If you talk to him when Akechi is at Leblanc for confidant 6, he'll tell you so:
(translator's note—学費 gakuhi, "tuition fees". If Akechi told Sojiro this, the chances that it is the whole truth are remote IMO—though I am attracted to the image of pre-evil Akechi working from a young-ish age to put himself through private school.)
Now, Akechi does not exactly endear himself to Sojiro on 8/28, when they first meet. But a week on, it seems as if Sojiro is at least trying to give Akechi a fair crack of the whip, and has maybe decided he's not so bad after all.
Later, on 10/22 when Akechi is on TV, Sojiro will ask if you ever heard from him again. You have, of course, likely not seen him since around 9/3 itself.
meanwhile in maruki's reality
Even within Maruki's reality, Sojiro is present for the explanation of how Akechi survived and turned himself in, on 12/25:
I can believe Sojiro missed most of the conversation, behind the counter like that, but no way did he miss Futaba's freakout here. He presumably knows who Akechi is at this point.
But by 1/2? He's forgotten. Wakaba is back, Morgana is human, everyone is happy, and nobody remembers that things were ever any other way, sure.
Akechi, though? He was never there. They never had that talk about school fees at the counter. Akechi never popped up on TV. If he was friends with Joker, Joker never brought him to Leblanc—or, in the original reality, Akechi never visited without an ulterior motive, meaning that when his crimes were erased from history, he never showed up at all. Not even for one of those shitty summer hangouts that waste a day.
So. Maruki ending Pleasant Boy is:
not familiar to Sojiro, because he never visited Leblanc;
not close enough to Joker yet to have spent time at Leblanc;
not a criminal and not dead, obvs.
I wonder how many other people he'd expect to know him simply have no memory of him at all.