Consider the position of the legs when running at top speed. When the foot is in contact with the ground, the leg is slightly ahead of the body and then travels back to slightly behind the body … before lifting in the air again.
Thus, while in contact with the ground, the leg is almost straight. Squatting takes place by bending the knees much much further than you would when running at top speed.
However, in the acceleration phase, the body leans foreward and depends on bent leg strength ie squat. So, this would tell me that squatting helps acceleration and even the start of the race… but little in regards to top speed.
you can think of it like that, but what about all those skinny guys who have rocket starts/super fast accelerations? and even improve on it without ever getting in the squat rack.