Ngl, I was surprised about him using Sinon's Solus Avatar too, but given he's using Alice I guess anything goes XP
I am a hotpants/shorts fanboy, i loved that one and if there is 1 request i ever make of Fujino is that Asuna and more girls dress like that at least in some scenes/parts xD, and yeah i knew she was corrupted just didn't remember if it was that guy or just some internet dude (some of the videos and posts were from others i think)
The thing i am most curious and excited about Sinon appearence is wether or not Cuckito realizes it was her he saw on the forum, or even if he will act on it. She probably will be involved in Suguha's plotline unless her whole appearence in the game has a background of breaking off from Hebishima and trying to get herself straight.
The one making all those posts bragging about fucking 99 women that included Sinon as "girl #99" and his 'progress' in "conquering" (Corrupting/blackmailing) Girl #100 (Suguha) was always Hebishima, for obvious reasons. Hell, if you go look back, you will see he somehow got Shino herself to steal the drugs he used in Suguha the first time she convinced her to go to karaoke with him somehow.
As for Kirito, he's specifically dumbed down to negative infinity like other Fujino "MCs" to be blind as all fuck, aka unable to recognize the girls online/getting videos of them sent being clearly someone they know when all that's censored is their eyes at best or when it's someone whose voice they have known for years. If he didn't recognize Suguha in those videos Hebishima posted or sent him to his phone several times, he probably will never realize Shino was that girl online either.
Also, she very clearly was still looking for Hebishima at the end of Part 1, probably because he had "dumped" her to fully focus on Suguha, so I don't know if she will either have "recovered" after so little without his dick. Then again, she was dressed all slutty back then and now she seems to have reverted to her Canon more covering clothes IRL so it depends on how Fujino wants to approach her. Wouldn't surprise me if Fujino did the same as Alice and despite how their relationship is nothing like in Canon he goes and has her "befriend" Kirito only to see Hebeshima with Suguha again and get corrupted all over immediately to hammer the "not-quite-NTR" feeling of "Another girl that in Canon liked Kirito is getting fucked by someone else", lol
PS: Anyone else a bit worried about that part of him "modifying the story plots to include more CGs"? Feels like he caved in to the 'pressure' of everyone whining of not being enough content for the first update of Part 2, hopefully it doesn't become a habit or he will burn out fast...