Just my 2 cents on this interesting topic.
Regular throw frame data:
Start-up: 3 frames
Active frame: 1 frames
Extra teching window: 5 frames after the active frame connects
Recovery: 21 frames
As long as your character is considered in “neutral grounded”* state by the time the throw’s only active frame connects, you can always tech if your timing is good.
Obviously, you can tech a throw by pressing jab + short at the same time as your opponent. But you don’t need to press jab + short at the exact same time as your opponent. The game gives you 5 extra frames AFTER you “get grabbed” to tech the throw. This is the reason why you see things like tech throws where the characters end up switching sides (happens when you tech some back throws very late) or the defending character is already in the air by the time he presses jab + short (e.g. Q’s neutral throw). The opponent’s throw animation starts as if it connected, but you can still tech during the first 5 frames of that same animation. If you fail to press jab + short during that lapse of time, you will get thrown.
*“neutral grounded state” meaning here that you still have active control of your character and he’s not recovering from a move, NOT that your joystick is necessarily at neutral. You have to be at neutral to perform a “press jab+ short at the exact same time” tech throw. But it doesn’t matter if you’re holding a direction or pressing extra buttons at the same time while pressing jab + short to tech during the extra 5 frame window. This is why you can still tech throws while crouching, but let’s not get into that now.
Alex jump frame data:
Pre-jump animation: 4 frames
Landing animation: 2 frames (where did you get this figure? I couldn’t find it… I’ll just assume it’s correct)
In my experience, you can always tech throws during your landing frames when you empty jump. Unless your execution is sloppy, the character on the ground will always be the one executing the throw since he has the advantage of being grounded. But it seems the jumping opponent can always tech because landing frames are considered “neutral grounded state”* as long you don’t perform any move after landing. So realistically, you pretty much always get 5 frames to press jab + short and tech throws after empty jumping, even though it would seem you’re technically at disadvantage in terms of animation.
I guess we could question the nature of landing frames then. Why can you always tech even though you should be at a disadvantage? When you block/parry/tech, it looks like there is no frame disadvantage. But when you take any other action (such as jumping, or sticking out a normal), the frame disadvantage suddenly becomes obvious --and you will get thrown before your move comes out, regardless of whether it is faster than a throw or not.
My personal guess is that the game lets you perform any defensive action during landing frames. I think the engine always follows the following rule, probably to prevent defensive abuse of throws: as long as your character can block, he can also tech. And since 3s has trip guard (e.g. blocking an attack during your landing frames), it also has what I guess you could call “throw guard”. 
EDIT: Also in my experience, you can still get thrown during pre-jump animation frames but cannot get thrown during pre-super jump animation frames. People usually don’t get thrown out of their jumping animation because it’s so quick, but it doesn’t seem to be immune to throws. However, you may be able to buffer a VF-style tech throw during your pre-jump frames anyway, but that would require precise timing and I have no way to really test it out. If that’s the case, then pre-jump frames would be the same as landing frames except you can’t block/parry. I could be wrong of course, but that’s what I’ve observed so far. Feel free to correct me.
