Except that, a Picoscale-singularity would evaporate. There is no "If it didn't", because it would.
Indeed. I really wanted to have a quick look up at what size (nanoscale, microscale?) a singularity could be expected to finely balance input (ripping the odd electron or even nucleus from the surrounding matter) and Hawking Radiation output, but I'm a bit rusty about current theory on that point, probably need to look up the Schwarzchild radius equation, for a start.
Consider it shorthand. I am largely going on the principle that while the smaller stellar-quantity massed black holes can deplete relatively easily in the vacuum of space (are unlikely to have enough nearby mass, in appreciable quantities, outside of the occasional unlucky star and/or its planetary system/protoplanetry disk that wander too close), depending on how busy the area of space is/becomes, it's possible that one can be much smaller if created on (i.e. just below the surface of) a planetary mass which manages to sustain itself (and at this point I was going to say "asymptoticly", but I mean this 'time-reversed') just above the 'inevitable evaporation' point, until the factor of increase drags the infinitesimal difference of mass far enough away to zoom off into full planet-consuming glory.
But, as I said, I'm a bit unsure as to what scale could be supported by (say) the density of mass found at the Earth's core (where a loose black hole may have drifted, munching away), and besides the odd electron or bunch of nucleonic hadrons might well be significant enough so that the absence means quick death and the presence means quick inflation, especially upon the rapid time-scale of such a small body, with such a large proportion of 'surface area' to volume (or, perhaps I should say, mass... given that a singularity would technically contain infinite volume) that is surely a factor.
Perhaps the art of 'taming' a black hole would involve careful and regimented feeding to keep it 'simmering' within a managable mass-range.
Anyway, the point is that I really doubt the whole "OMG, the LHC will end the world!" idea, in the first place, but even if it does, it would end it quicker than four years. It's just too hard to be inevitable but so much delayed. Which is very much the direction of your objection to the petard that I'm supplying the design for, interested as I am to see if they find themselves hoist by it.