"Aformentioned Stasis Spell"
You mean this one? I mean, the fact that it's classified as a transmutation spell doesn't really lend credence to your argument. You're going to have to explain how it works more in-detail because many of the descriptions I'm reading from it right now are not at all how timestop works. Body functions "Virtually" ceasing is not timestop, as Body Functions don't "Virtually" cease; real Timestops flat out justs stops all functions period.
"A boatload of simple ones that offer enhanced speed via acting faster (heightened time)- Haste, Hustle, Knight's Move, and so on"
None of which is on the level of Timestop, so...
"Slow, which is the same as stopping time except less effective. Luckily this is a low-tier spell."
For gods sake, resisting Time Slow is literally infinitely weaker than Timestop. Not a good resistance feat. Even if someone had 99.99999999999999999999% Time Slow, Time Stop is INFINITELY stronger.
"Aging Touch, which speeds up time for the target and causes them to take "age damage". There are several others like this, too."
Again, Time Speed Up and Time Slow Down are infinitely weaker than flat out Time Stop.
"And finally. Mind Flayer can read minds. As a thought. If Ainz does open with the stuff you say he does (I doubt it, I feel as though this is being bent in his favor because who honestly cares), MF can do the same. Read thoughts."
Reading minds means, honestly nothing here since what can Flayer do? Seriously!
Flayer reads Ainz' mind, sees Ainz is casting Discern Enemy and about to do timestop. What then? Ainz isn't going to actively think "He's going to kill me in one hit, but I have revival items! Mu ha ha ha!". So mind reading is actually just worth nothing here.
I can source all of my information if you want.
Time Resistance is essential in PvP. Meaning Timestop resistance is nothing new for avid PvPers such as Ainz
I can't find the link for this since it isn't in the anime, but Ainz also uses timestop on Foresight (The Worker group) even though they were a complete non-threat just to drive home that Timestop is a normal thing he uses in combat.
Ainz came to recruit these guys but after humouring the troll and learning more about their biology, along with some slight torment from said biology lesson, killed them all immediately after her got serious. This is against fodder that can't even budge him.
The first spell he tries out is his favourite one; Grasp Heart. It's instant death and even if it fails, it stupefys the enemy. Perfect for PvP. Stupefy is different from stun since stupefy is basically stunning for the mind; unable to think properly. Same effect in the game though.
In all of these scenarios, Ainz already did previous information scrying and knew for a fact that literally nobody would ever be a threat to him.