My interpretation of course carries no weight since I am not a bishop, and bishops traditionally interpret these canons and apply them (with exactnesss, or economy, and in a manner they deem prudent). However I believe that any bishop who has need of canonical backing regarding, for example, the ineligibility of voluntarily castrated persons for holy orders, has everything they need in Canon I of Nicea.
As an odd aside, I would note that Canon I seems to be the opening round against Origen, whose sepf castration was noted by his professed admirerer Eusebius of Caesarea, who in turn interestingly was the one bishop out of the 318 who acted with reservations and is historically regarded as indifferent on Arianism or a soft Arian himself. One cannot help but wonder if people discussing Origen's castration and whether it was coerced, voluntary or semi voluntary had an impact on the creation of this canon. I would appreciate if anyone knows of any good, extensive, English language resources on the history of Nicene canonical legislation.