All that unsafe does in these cases is enable the "unsafe super-powers" which the compiler can't check, thus shifting the responsibility onto the author. But for example if you've got some code which doesn't borrow check, and you just sprinkle unsafe keywords on it, now you've got code which still doesn't borrow check and diagnostics telling that this unsafe keyword was futile and you should remove that.

I haven't reviewed this code, but the percentages described don't sound like they'd need a huge architectural overhaul to use much less unsafe, it might take more actual human effort than they want though.