I just rewatched the episode the other day (also knowing it would be up for the rewatch post! ^_^) and I really found this super interesting to watch again. Shen Wei is, IMO, not even trying to play The Harmless Professor here. His attitude towards Zhao Yunlan is 100% consistent - as soon as Zhao Yunlan is in the room with him, he's switching to earnest* and really straightforward**. But from his general demeanour, you'd expect him to try the harmless professor with Zhu Hong and Chu, and instead he's basically dissing them. It doesn't look like a sudden loss of control either, though I also don't think it's the smartest strategy - if he didn't have the kind of rapport with Zhao Yunlan that he does, his interview behaviour would be likely to get him more on their radar rather than less.

It's one of those moments where I'd expect Shen Wei's character type to do something, and Shen Wei the character does something very surprising.

It's very interesting, yes! We see him be a harmless-ish professor in episode 1, but here he seems to be accidentally stuck in Envoy mode for some reason. Maybe he's just super pissed that he was interrupted by the SID?

Shen Wei is really not coping well with "Zhao Yunlan might not like him". (I actually think Zhao does have a bit of a legitimate beef about Shen Wei's timing. I mean, it probably wasn't Shen Wei's fault, IDK what his Dixingian Trouble Alert System is like, but it's true that they really could have used the Envoy to show up a little earlier, and it's a pattern, and the Envoy is now all serious and mighty about The Rules... it's really no wonder Zhao is pissed off.)
Indeed! And I agree that Zhao Yunlan's beef with the Envoy's timing is completely legitimate, and the Envoy should probably start investigating options into getting a better Dixingian Trouble Alert System. Currently he's the deus ex machina at the end of the exciting bits, when he really should be there at the start to stop whatever it is from happening, or at the very least appear in the middle of the exciting bits to take over.

I'm actually a big fan of Zhu Hong's dress in this, I think it looks killer and is visually great in all the darkness in the scenes she's in there. I do find it interesting that they were quite explicit at the start that she's not a field agent - there's her "I'm a secretary" talk, and Chu also says at some point that he's the only field agent of SID - but that seems to have fallen by the wayside later, when she's out on missions and investigating. (I'm hoping her pay got adjusted. *g*)
I agree on her dress, it's quite killer! Re: the field agent stuff – IIRC most of the "field agent" stuff we see her doing is not really going into danger, except the Hanga arc field trip, where she's there as Wang Zheng's female friend. Then later on, when the personnel is tight, she gets enlisted into doing more field stuff.

The other thing I found noteworthy while rewatching this was that Shen Wei is really a little... reckless... in how easily he gives away what his biggest liability (Zhao Yunlan) is. It seems terrible strategy to on the one hand say, 'I can't tell this guy I love who I really am because it might put him in danger', but then paint a HUGE TARGET on him by telling the currently-main villain du jour that the villain is absolutely not allowed to touch him. I mean, I love you, Shen Wei honey, but that was not good self-control!
Indeed. It's every terrible superhero identity thing rolled into one. I now want Zhao Yunlan confronting the Envoy about why the Envoy went to such trouble to specify that the villain isn't allowed to touch him, and if the Envoy is going to paint such a large target on him, he'd like some forewarning, thanks. Or just more Zhao Yunlan calling Shen Wei out on his bullshit, even if Zhao Yunlan seems to have gone for the "judge nothing and make encouraging noises so maybe he'll tell me something later as well" approach. No, Shen Wei, no indeed.