If the "ocular migraines" appeared more than a year later, they are extremely unlikely to be related to being hit in the head.
To answer your question, yes they are being overly broad in what they are characterizing as ocular migraine. While the International Headache Society's classification schema for ocular migraine is itself purposefully ambiguous (because unlike things like heart attack or HIV, primary headaches are based more on clinical history than a specific test that can prove it's X or Y), a truly "ocular" migraine would be limited to one eye and involve "negative symptoms" (i.e. loss of some normal function). An example of a negative symptom would be loss of vision (as the blood vessel constricts during the migraine). (Remember, headache is a symptom of migraine. Migraine is actually a vascular phenomenon--involving vessel constriction and dilatation.) One can have an aura with an ocular migraine; but a true ocular migraine will be unilateral (whereas auras may be bilateral or unilateral) and will almost always involve a loss of function (blurred vision, loss of vision, etc.). Pastel geometric shapes is a "positive symptom"--or a symptom that's a "gain of function," if you will. You're "gaining" things in your sight that aren't really there. The geometric shapes are more consistent with just a visual aura rather than "ocular migraine."
When explaining things to the laypublic, physicians sometimes try to associate similar conditions in their explanations to avoid being overly technical and maybe even confusing the patient. For example, when telling a patient he/she had a stroke, a physician might respond to the question "How did that happen?" with an answer like "You had a blood clot go to your brain." That's easily understandable for most of the laypublic's purposes. The most technically accurate answer may be "You had a soft plaque in your internal carotid artery that ruptured, causing platelets to aggregate and activate to form a clot. The clot then dislodged and traveled to your brain, blocking an artery and keeping oxygen from getting to the brain cells. So the brain cells died."
So I have seen that in cases where the "technical" aspect of a disorder doesn't so much matter in terms of treatment and such, many physicians (maybe all of us) will generalize. In most cases, migraines are treated the same regardless of type. (There are some exceptions; but this is "in general.") So since it involves the eye, they may have used the term "ocular migraine." I would have said "migraine with aura." For me, a true ocular migraine means significant potential (not extremely common to occur, but significant potential to occur) of vision loss as a result of the migraine. A visual aura associated with migraine doesn't carry nearly the same risk.
As for what websites may say, one must always evaluate the source of information. A journalist or another layperson or a physician whose specialty doesn't include headache under its banner (e.g. a surgeon trying to explain headaches) may write things on websites that are generalizations or assumptions or just flat-out false information. If you've ever seen Sanjay Gupta on CNN or Nancy Schneiderman on NBC talking about medical topics, they commonly talk about topics outside their area of expertise and say things incorrectly (It grates on my nerves; so I don't watch them.).
Now, on to your last question. Neuralgia has been known to occur spontaneously, after major trauma, or after seemingly totally benign trauma. That's not terribly uncommon. But it's difficult to prove that a given event caused the neuralgia. Most neuralgias of the face/head are treated similarly; so once again, the cause doesn't matter as much as the treatment. (Note, there are several important exceptions, such as tumors or vascular malformations that can cause neuralgia and obviously need to be treated much differently than more typical neuralgias.)
Hope this helps. In the end, it sounds like just a semantic issue--"ocular migraine" versus "migraine with visual aura."