For playing Osttruppen, it is a usless tech. That's why it also gets unlocked with T2 since last patch.
So or so there were scenarios that happend. And the Question isn't about that, only changin ability a. with a less OP ability, with option b. getting it back, when needed.
Have you ever played osttruppen in your life?
The moment opponent gets HMG, you are either forced to camp your fuel, praying to get flame 251 and hope he won't have anything to hardcounter it by that time or to build a mortar/sniper, which will be needed, because osttruppen alone are good only for map presence in first minutes - they scale well, but you aren't going to win anything without anything capable of doing damage.