It is situational, and I tend to approach it the same way as I approach hypoglycemic patients. I have kind of a mental check list that applies to either one (or really any other chronic condition that can have acute flare ups, like asthma).
First off, does the patient have a history, and who called? What preceded the situation? Trauma? Stress? Flashing lights? What is the patient's normal baseline (one seizure a month, one a year, none since starting medication). What type of medication is the patient taking? How fast is the situation resolving? What do the patient's vital signs look like? Were there any secondary injuries sustained (bitten tongue, fall trauma).
I look at the patient over all, does the patient look like they have the ability to take care of themselves? Do they have their medications and are they taking them? Do have a primary doctor to call?
This is a patient we left at home, which kind of illustrates how my thought process works.
18 year old female, at college living in the dorms (family is in the area). She has a witnessed seizure in her dorm room while sitting on her bed. Her roommate called 911, and described a generalized seizure (I don't remember the exact details of length or progression). Pt was nearly totally alert and oriented when we arrived, and within a few minutes had GCS of 15.
She had been diagnosed with epilepsy as a kid, documentation was on file with the dorm Resident Manager. She told us she had seizures around once a month, and they were generally triggered by stress or illness. It had been a few weeks since her last seizure, and it was the beginning of midterms that week. I can't remember her meds or vitals, but I there wasn't anything crazy (like a pulse of 160 or something). She had been sitting on her bed and hadn't suffered any injuries.
The patient didn't want to go, and hadn't gone to the ER for seizures in some time. She volunteered to call her parents and her doctor in the morning. Her roommate knew she had seizures, but had never seen one before and fully admitted to panicking when she saw it and called 911 automatically.
So essentially, the pt experienced a seizure that was normal for her without any complications and she didn't want to be transported.
Now, had there been concerns about any of the above issues, I likely wouldn't have agreed with the no transport. Even the fact that the pt was local played part, because a college student who isn't local may not have had a GP in the area that they could go see, meaning they may not have been able to get prompt follow up.*
There are a ton of variables...Say this was the patients second seizure in a week, but she had already scheduled an appointment with her doctor, and it was the next day. I would be comfortable with her refusing seeing as she is being proactive about addressing the issue.
When it comes down to it, it really depends on the patient, what is normal for them, and what they want to do.
I guess my core point is that in some patients seizures are normal, that is their baseline. So part of your assessment should be determining if what they experienced is a deviation from their baseline or not.
* If patients without GPs continue to refuse transport I will usually take the time to track down the names/phone numbers of the student clinic, or the local walk in clinics, or low income clinics or whatever it is that suits them.