Personally, I think they can but it's more fun to draw your own conclusion. I don't think very often they would be fully human and male, like an insanely low chance as opposed to 0%. This is mostly because we've seen races of all sizes in females. Most races exist in males too only in small sizes. So, it's not that big of a stretch for a female human giantess to exist. Not to mention magic (growth), potions and whatnot. The bab I assume would just syphon only what it needs from its giant moms placenta regardless of size. But, breastfeeding and twins that's where it gets 'iffy'.
I think she was just referring to physically having as opposed to birthing pure human males when she said "Male in any race" since its prefaced with kidnapping. Naya and Madea are Lycalian, but there are small male Lycali(hybrids). You just obviously have to be female to be born giantess or be a guardian and not race mix outside your own, mix with anything besides a pure human, or have sex every night for 10 years to have kids. There are males of almost each race in small sizes. Could just be a writing error too though honestly
"there are" instead of "there's"
. On another note, Sheina might be an ideal example since she looks mostly human. But these are my ramblings.