So I read about the Void nights and stuff so I thought are most Khajiit loyal to Altmer and why don't Altmer refrence them as dirt because they are beasts?

They aren't loyal to them. More like they won't get involved but will let thalmor move troops through Elsweyr and possibly spare supplies for them

And the thalmor don't antagonize them because they don't want them attacking the dominion.

Typically the Khajiit and Bosmer haven't got along well. And having another force attacking your forces is generally a stupid thing to provoke if it's completely unnecessary.

If the thalmor goals come to fruition though, you'll see elsweyr come to an end shortly after they have no more use for them.

It seems like after the Thalmor took credit for restoring Masser and Secunda, the Khajiit revered them as saviours.
The Thalmor surely thinks of the Khajiit as unworthy beasts, but perhaps they're going soft on the Khajiit and instead focus their racist hatred on humans, Argonians and Dunmer?
If most of a race rever you, it doesn't seem smart to openly talk about how lowly they are.