I'm not saying it would "guarantee" the Eastern Roman Empire's future - of course, it wouldn't. But I can't believe Basil considered his DNA faulty and therefore he didn't want to produce offspring. Tens of other emperors got married and had heirs probably just because they had to. Most of them didn't marry their childhood or teenage sweethearts - their marriages were arranged according to the interests of the state.
I refuse to believe that an emperor like Basil would put his monastic vow (was this also a celibacy vow?) above the interests of the empire or his own vanity at that.
Okay, let me see if I can explain what I think Basil's POV is.
Basil, for most of his life as of his ascension, has seen the throne occupied by powerful generals with zero claim to it (from 963 on). Hell, him claiming the throne in his own right sees a goddamn rebellion by Bardas Sclerus within a few months.
And he continues to have troubles maintaining control of the ship of state for another thirteen years.
At that point, at all of thirty-one, Basil has every reason to not want the powerful as close to the throne as his father in law inevitably would be. That leaves either marrying a commoner or a nonByzantine, both of which would be highly unusual to say the least.
Meanwhile, his younger brother is married with a few (two or three) daughters and may God willing have a son.
So there's little reason to fear that the dynasty will go extinct if he doesn't marry, or that any other bad things will come from the throne going (should the Macedonians remain in the purple) to a nephew instead of a son.
As such, the interests of the empire - even if one sees them as tied to this particular family (and given the nonhereditary nature of the Imperial throne, why would one do so?)
are not at stake.
That's before getting into any fear of women, lack of interest in sex, homosexuality, whatever. There's just nothing much that makes it a good thing, and with his brother having children, "because they had to" as with Leo VI doesn't really apply.