So lets count the ways Frieza loses to Thanos:
1. Frieza has no feats resisting TP attacks and Thanos is one of the best TP guys in comics. There is nothing to suggest Frieza has the mental defence to resist a TP attack from Thanos.
2. Thanos has a force shield durable enough to take shots from Galactus...so unless you're going to argue that Frieza>Galactus then explain how Frieza will even hurt him.
3. Thanos stood quite nicely to a fight against a PG wielding Thor (who wreckd a team of top tiers) and Odin, so Thanos has the physical durability to survive a fight with a peak skyfather even without a force field.
4. Thanos has reacted to bullrushes from SS and the fallen, who both travelled at FTL speeds so his reactions are easily some of the best in comics today.
5. Thanos had the energy output to physically knock Galactus back, and I doubt I need to tell you how powerful Galactus is.
So in other words here is the problem:
What evidence do you have that Frieza can avoid being mind raped?
What evidence do you have that he can get past a force shiled from Thanos?
What evidence do you have that Frieza's stirkes or Ki blast will even flinch Thans?
What evidence do you have that Frieza is faster then what Thanos can react to?
What evidence do you have that frieza could survive a attack (either physical or projectile) from Thanos and avoid being oneshotted?