First traditional Mead question

First off welcome to Gotmead
Also, sorry to hear about those bees

I can see no reason to add nutrient when ferment subsides. having left over nutrients is a bad thing because it will only serve as food for spoilage bacteria. Assuming ferment isn't stuck/slowing because of nutrient deficiency.. But even then you wouldn't rack to secondary in that case and adding nutrient may not be the best solution. Maybe you're confusing something about staggered nutrient addition (SNA)? In the case of SNA nutrients are usually added only until the 1/3 sugar break. Maybe a bit later for high gravity musts but I'd have to check on that (yours is not a high gravity must anyway). In your case the 1/3 sugar break would be when you reached an SG of 1.067 (no need to be EXACTLY on the number). While airlock activity is no precise indication of what is happening, I usually tend to have more activity by day 4. However, your temp is lower than what I ferment at so your activity should generally be slower anyway (and I never used D47)
Check out the SG and see how you stand in relation to that 1/3 sugar break. If you have not already passed it, you can add some nutrients if you think nutrients could be an issue. Don't overdo it because that nutrient should ideally all be eaten up by your yeast till the end. You can also aerate the must until that 1/3 break.
I can't say whether or not your 1/2tsp energizer is enough because you haven't stated what you used as energizer

Btw aerating would consist of shaking that mead for 3 times a day until that 1/3 break. Some aerate less than 3 times, and others only do it for the first 3 days. mead making is like that, everybody does it slightly in their own way
*Maybe* the other person was referring to stabilizing your mead which would require campden tablets and potassium/sodium sorbate.
I think that nutrient is very close to DAP (Diammonium Phosphate). Just so as to give more info for future reading: DAP provides a lot of nitrogen or YAN/FAN but not a lot of other nutrients which yeast might need like Fermaid K (Or maybe tronozymol for europeans) does. Don't worry too much about the more intricate stuff now that nutrients are already added, just something to read about further
1/2tsp of that nutrient might be just enough. Depending on your hydrometer readings you will know exactly how much sugar your yeast has eaten and how fast, and according to your readings you might add some nutrient before that 1/3 break to help give your yeast that extra push to help it finish your mead.
I suspect this mead might not finish completely dry. I tried using the minimum nutrients on a couple of batches and they finished around 1.010