Egg Toss has an animation before it comes out, anyone can see it and react, and Megaman is going to stay like mid to max egg toss range, and it takes time to actually travel that far, literally unless youre practically decking them in the face right in front of you with an egg, people can react to them. Add in the fact that Megaman's short hop is SUPER low, his fast fall is really fast, his fair and lemons beat out eggs and are easy to hit eggs with (Ive played as Megaman against a Yoshi, hitting eggs out of the air with Megaman is easy peasy lol), so a simple double jump aerial will deal with them if need be, his fast fall is fast enough you can land right after no problem with another lemon. Also, his short hop lemons are like, what, 10-15 frames total? Thats more than enough time to finish and defend from a mid range egg toss and shield or whatever. Just try playing the match up from Megaman's side, even without the technical skill, just being aware of what works as Megaman against Yoshi you'll see what I mean, it is actually really easy to deal with eggs as Megaman.