Ok here are the advantages of not trying to get a great scientist to bulb machinery...
1) We don't have to tech aesthetics (468) or alphabet (468). Now teching alphabet has its own benefits, but it really is unnecessary for optics.
2) We can tech fishing when we want to. And I think we really want to tech fishing long before the great scientist will come. With fishing we can build a workboat and settle a strong Marble/Fish city much earlier (and this site is at some risk to Toku). And then with sailing we can start building the trireme that we want to upgrade to caravels long before we get close to optics.
3) Bulbing Theology earlier and building the AP without whips and chops saves the forests and population in Delhi. Instead the forests near Delhi can be used to chop into the Pyramids for failure gold that will further accelerate our teching. Or the forests can still be used to chop into the AP. Getting the AP ~10 turns earlier could be quite advantageous for several reasons. First, building the AP makes contact with all the AI that may have gotten Hinduism with random spreads -- which at the very least might mean we get a few discounts on teching things they know, at best it allows us to make contact with an AI that might be willing to tech trade with us possibly getting us alphabet for free. Second, the bonus hammers on the 1 or 2 monasteries we might build. Third, it gives us a bit earlier protection from Toku with AP peace vote or allows us to call a holy war against him in the event he declares on us.
4) I think it works very well in combination with teching currency instead of alphabet. Currency is a superior tech for accelerating our own tech pace for building wealth is better than building research (if we have any research multiplying buildings). It gives us an extra trade route per city. And it allows us to trade resources for wealth from our neighbors. (also allows begs but I don't expect we will have anyone at pleased for some time to come).
All of these advantages were seen in my test games that I played about 7 days ago and posted on the site, but I wasn't very clear about these advantages in my posts explaining them.
Thanks for the clear and detailed explanations,
bcool!
Although I'm already more or less convinced here are a couple of thoughts regarding the issue which might be interesting nonetheless.
1) Any Toku personality which we manage to get to pleased (tech-trading threshold!) will happily trade us Alphabet (e.g. in exchange for Aesth) irrespective of how many of his contacts have it, provided he teched it himself with no-tech-brokering on. This is because Alpha has a monopoly value of zero, just like Fishing, Animal Husbandry, Monotheism and Monarchy rendering Toku's problematic iTechTradeKnownPercent = 100 irrelevant. The Toku personality also likes to tech Alpha early (as we are seeing) due to his leader flavor SCIENCE = 5. Liberation of a city to Hammu and getting +1 for resources will get him to pleased, it would of course be better to accomplish the often mentioned double-liberation for permanent +3, so that no resource trades/gifts are required for tech trading and open borders at pleased.
Aesth and Poly set us up for Literature and the Great Library. We are philosophical! I know it is all about playing the map, not playing the leader ...

I don't have the SGOTM experience where earliest finish date is the goal, how to assess the worthiness of later World Wonders. Are there rough estimates from previous SGOTMs for predicted finish dates, let's say we aim at 900AD - is the Great Library worth taking into consideration, with Marble and playing the Philo Gandhi?
2) Fishing could probably be traded for on T92 (after Machinery bulb) and a WB chopped immediately - are we sure we'd lose a lot of turns and delay setting up the coastal cities? When will we settle them? Don't we want to grow a bit first before building more Settlers? And don't we want to liberate a city to Hammu first, before he blocks all settling spots? Is 4

from a Crab for a couple of turns that much better than 3

from the Banana?
3) We are probably going to found Christianity with the early Theo-bulb competing with Hinduism when it comes to spontaneous spread of religions.
Maybe I underestimate the power of fail gold, probably because I don't really like the whole concept and usually don't use it (enough).
4) Yes, Currency will surely be useful, but we should get our hands on Alpha soon anyway in order to move a Spy eastwards through Toku's lands.