For the first paragraph, a better translation would be, "We cannot announce a mobilization." The second portion is more difficult.
As it is written:

Если честно, то чисто технически это остается единственным шансом удержать ситуацию - мы уже в режиме тотальной мобилизации. Но в таком режиме долго быть нельзя, а у нас со сроками неясность и будет пока только хуже.
How I'd translate it:
If I’m honest, from a purely technical standpoint, there remains only one chance to hold onto the situation - we're already in the mode of total mobilization. However, you can’t stay in such a mode for a long time, and our deadlines are unclear, and it will only get worse.

So to answer your question- They are already mobilized, but it isn't considered "large-scale". At the moment some 200,000 or so troops were mobilized and sent to Ukraine, but they are afraid to actually announce it to the public, hence we are hearing the "we were on training exercises" and "special military operation" lies. I assume "large-scale" mobilization would be something like calling up every able-bodied male to service for WW3? The only definition I could find was "the accumulation of large, poorly trained and under-armed insurgent forces."