It is my opinion that the author of the second link you referred to is inaccurate when she writes: "If you are eligible to make salary-deferral contributions but elect not to, you are not considered an active participant for that year." In cases where I am not sure, I prefer to go to the horse's mouth and read what the IRS has to say.
But in further looking at it, I think your situation might possibly be one where you are not covered. Reading in Pub 590, I find: "A special rule applies to certain plans in which it is not possible to determine if an amount will be contributed to your account for a given plan year. If, for a plan year, no amounts have been allocated to your account that are attributable to employer contributions, employee contributions, or forfeitures, by the last day of the plan year, and contributions are discretionary for the plan year, you are not covered for the tax year in which the plan year ends. If, after the plan year ends, the employer makes a contribution for that plan year, you are covered for the tax year in which the contribution is made."
So it looks to me as though if you did not make any contributions *and* your employer did not make contributions to your account, then it looks like you would not be covered. TIL.