I here what you are saying, and ever so technically viability may decrease after 30 minutes, but it is no different than leaving liquid yeast to sit out for 30 minutes so the difference is negligible. In the
Dry Yeast FAQ sticky in the Fermentation forum I linked to the Fermentis Tips and Tricks, and they discuss lengths of time it is acceptable to wait before pitching after hydrating.
And I love the imagery your post brought to mind
EDIT: Here is the info I found regarding delaying pitching after yeast is hydrated:
How quickly do I need to pitch yeast once it has been rehydrated?
Once the dry yeast has been reconstituted, you have a window of time to pitch the yeast with minimal risk of contamination that is dependent on temperature. If the yeast is being stored at 25C, you should pitch within 4 hours; at 20C you should pitch within 6 hours; at 4C you should pitch with 18 hours.
Keep in mind, it is a best practice to pitch the yeast as soon as possible. During the first 30 minutes, the yeast is given a boost from vital nutrients that are packaged with it to help energize the yeast as it enters into its growth phase. Waiting longer than the recommended 30 minutes causes the nutrients to be exhausted and the yeast will want to go dormant, increasing the chances that you'll see a longer lag time when you pitch it.
And the link to the Fermentis Tips and Tricks:
http://en.calameo.com/read/0026934555f07e32293ea
And the quote from Clayton Cone about the 30 minute time frame from
this link:
We recommend that the rehydrated yeast be added to the wort within 30 minutes. We have built into each
cell a large amount of glycogen and trehalose that give the yeast a burst of energy to kick off the growth
cycle when it is in the wort. It is quickly used up if the yeast is rehydrated for more than 30 minutes. There
is no damage done here if it is not immediately add to the wort. You just do not get the added benefit of that
sudden burst of energy