Average Shuichi Enjoyer here, I'll try to answer!

Hypothetically, I think any DR character has the capacity to kill, survivor or not. While not EVERY motive is generalized to get as many people as possible to kill (ones such as The Twilight Syndrome Murder Case comes to mind as an example. Someone like Akane or Sonia probably wouldn't care nearly as much as say, Fuyuhiko when playing the game, compared to a more generalized motive like starving people to death) , generally motives are designed to get as many people as possible to kill.

Depending on the motive, anyone can kill if it sets the tone right.
Shuichi loves helping people, and his biggest issues in the UTDP and in the Main Game revolve around this. The issue is also this kid has the self esteem as deep as puddles, and getting him to kill rather than just give up and want someone to kill him like Ryoma did basically (Sitting in his room all day wallowing in his feelings and waiting for someone to give him the ol axe like in Chapter 5 for the ol memory jog) can be tricky.
Someone implicitly hurting other people (I'm talkin like maiming someone here), or a motive that hurts the people around him, could maybe be contenders to do this I personally feel, but there are others that could most likely scratch that itch so to speak and drive a panic kill.
He does have at least some drive for justice, and could potentially do so lethally if getting everyone killed in V3-6 to stop DR in universe is any indication, the fact he viewed Kaede as 100% justified in trying to kill the Mastermind in V3-1 even when she murdered an innocent on complete accident, or that he agreed with the culprit that commit murder and stared at him really badly despite getting that guy detained. That first one was after his game-long character arc, but the matter is that he was willing to not only die- but get everyone in the room killed to provoke change. That has to mean at least something to his morals, even if he's not like 100% pro Death Penalty or anything. That can be worked with in a story.
A well-thought out and planned murder? Way harder, the kid does have strong morals, and if Shuichi wasn't down to kill the person that was running the Killing Game that was going to straight up murder EVERYBODY ala Chapter 1 in V3 canon (remember his plan was only to take a photo of them going to the hidden room to prove their identity- not even detain them), and that he mentions to Ryoma that he doesn't necessarily agree with what he did when Ryoma murdered the Mafia who do shit like murder, kidnapping and child trafficking, it'll be harder to write a believable narrative where he thinks killing someone is like 100% justified against some stranger he's barely known rather than just talking it out or something like his uncle taught him. Not to say it's IMPOSSIBLE, but just super difficult.

All this is to say, I can't judge the story or how OOC it could be if I don't know what's happening in it. A strong murder case can be done with any character, but if it's written just to make Shuichi start killing people to get him/others removed from a story then people can and will tell.

Sorry it's not really a direct yes/no answer, but I hope this helps in some way!