I could never figure out why the Reds had to lie about everything.
There was no scandal, security or propaganda casualty to be suffered if the truth was reported: a national hero was killed during an aviation accident. It happens all the time, and I'm sure Gagarin was well aware of the hazards of his profession, and accepted the risks gladly.
And I'm sure he would have preferred a quick, painless death in the saddle, with his boots on, fighting that spin all the way down, than tube and wire time in a hospital bed.