Making statuses too dangerous takes Spiral Knights along a path of difficulty it doesn't need. The statuses have to be an inconvenience that can change the tide of battle, not be things that make you immediately fall in battle. Spiral Knights is not a game that is unforgiving, and especially since status is inflicted by an RNG, it's not the best thing to change.

Changing AI behavior is a real difficulty change - we see that between tiers. The strength of statuses already increase per tier as well(Or at least I think they do). No need to change their behavior, at least in such a drastic way.

All the enemies you listed just don't work under the same circumstances as other weapons might. That and they are very powerful against anyone with even a small bit of lag.

Scarabs shouldn't deal damage after they hit the ground, but the animation is just that - an animation. The answer is to be careful.
Glop drops are the bane of my existence but that's just my problem. They work just fine, and the whole point of minis is to not let them come at you in numbers.
Gorgos are just weird, but predictable. Up until tier 3 they're pretty simple, but that three-bite attack plus the sways let them move across distances that even I can't.
The solution to all of these enemies is bombs. Or with gorgos I've found an AT cutter shreds them to bits.

All of these AIs pose a challenge, but all that is needed is to find out why they are challenging. These are also the newest enemy additions to the game, and haven't been hit by the nerf sword yet. I say let them be powerful - knights are powerful enough as is.

I think if what he means by higher difficulty, he means a future if possible tier 4 aka the core and if the run was set on elite then these statuses would come into effect. But i have to say these statuses need to be balanced out or everyone who goes in the core will be killed off before they get to have a look around.

Counter to Shadow Fire is Vog and pentas
Counter to Absolute Zero is a friend with DVS
Counter to Venom is Full Ancient Plate+Pentas with Max Poison resist UVs and Omega Shell, and insane dodging skills... Or just a remedy
Counter to Tesla is Mercurial and not standing near allies
Confusion is literally a terrible idea so I'm not even gonna try
Death too

But the first 4 are interesting. They definitely make Chaos worse. :) I would drop the part where shadow fire can't be cured, though.

One thing I would suggest: Make Absolute Zero have an amount of damage that needs to be dealt to free a knight (or monster) from it. 2,000 in T3 seems about right.