You play the Diddy matchup fairly well actually. The only thing I can tell you is to pick up a bit on player habits and try to punish those more or read them a bit earlier on while playing so you can have a bigger sense of security while playing.
AZ for example rolled a lot in certain situations. If you saw this, you could chase him and try to punish, or when you think that would happen spend time trying to maybe get the banana behind you or just getting in a better position against him. That's generally what I do when I know someone rolls a bit, I either punish it or if I think I can't, just kinda respace myself in a more comfortable area.
Another thing I noticed was that from the ledge, AZ would drop down, Upb to the edge 1 or 2 times, and then jump up from the ledge. Usually this was accompanied with a Fair as well. If you spot something like that on the edge, you can either punish them before their attack comes out/after they have barely jumped off the ledge, or you can bait the Fair, move in and punish. For a move like Fart, doing that as they jump up is a tad easier, where as for like Uair waiting for their Fair to come out and then hit them works better. Also from the edge with good timing, you can Ftilt them and it can cover a lot of whether they jump up, stand up, drop down and misspace the edge snap, etc.
The only other thing I can think of really is that with a good enough lead, depending on how confident/good you are at it, you can go ahead and try to time Diddy out/play keep away. While doing this, you obviously try to avoid Diddy's stronger moves while at the same time making Diddy fight on your turf, in the air. This makes it easier for Wario to get in safe damage while also avoiding the traps like Banana slip/trip into Dsmash/Fsmash. This is even more powerful if his Fair has already been staled, as each time he uses it he basically doesn't get that much closer to killing you. If he's used it even 3 times or so, the killing power on it is drastically reduced to where you can reasonably live up to 180+ with good DI/SDI and not getting hit by moves closer to the blast zone/super super high up Uair.
You can beat Diddy without camping him IMO, and you certainly proved you can handle most aspects of that matchup well, but combine that with running away a little and I think Wario can be a nightmare for Diddy. This is only if you feel confident in doing that, otherwise just keep doing what you do and don't worry about it. I don't always time out Diddy players when I play them, but I usually do try it in a single game or in serious friendlies just to see how they respond to it/see how I can abuse it.
Edit: Fthrow and Uthrow are much better to use against Diddy than Dthrow in MOST situations. I say most because sometimes there will be a banana you control on the ground right where Diddy will land after Dthrow which will allow you another free grab/hit, but besides that it's almost universally better to try and Fthrow/Uthrow him. Fthrow secures 13ish Damage on him, can be more with pummels, and against light characters it's better to get guaranteed damage than around half that damage non guaranteed with somewhat ok follow up options. Fthrow and Uthrow also place Diddy IMO in a worse spot than Dthrow most of the time. They keep him in the air, Dthrow he lands and can shield/try to outplay us there.
I will say however that I prefer Fthrow most of the time to Uthrow. I am not that fond of Uthrow most of the time, but that's just me usually since I like to get the most guaranteed damage out of a throw if I can without needing to read that hard for extra damage.