What risk, do you know how much mea there is there ?, do you know if there are any cracks ?, do you now how deep the hole is ?.
At the end of the day you can DIY with a cheap helicoil kit, but you can also pay someone a little extra that knows their way around alloy repairs to do a much better and stronger job with a plug that is GUARANTEED and for not much cash, as I said it's up to him what he does does not matter to me, might mean another cossie breaking for spares soon though!!
tabetha