Naw in the books the Q are a cosmic entity, the result of evolution of matter creating a continuum called Q which happens by error of ancient aliens to be connected to our continuum. They are not subject to the biological principles required for assimilation typically.
The reason Q would not want the Borg so antagonized is that in many things the fate of their continuum and ours depends on the Janeway timeline ending with her early death which happens in all the multiverse. It is the Star Trek equivalent of a fixed point from Doctor Who. Going so far as in one universe she is said to have slipped and drowned in the tub despite the far advancement of the Trek universes. This is because in the main Trek universe she destroys all the Q accidentally by severing their link to time and therefore destroying their ability to grow into life. This was done in an attempt to save the multiverse from destruction at the hands of the equally sentient Omega continuum.
The Q though cosmic in origin could become a humanoid or otherwise bound species like Q did that one time or Quinn. The knowledge which they posses would give the Borg such a great advantage that they would surely assimilate the universe if other Q did not intervene. Also the supernatural powers which Q have access to outside of their continuum would so allow the enlightened Borg to resist cosmic entities.
Here is a citation from the Eternal tide between the two new Q talking concerning Janeway's death.
"They had given up being Q before they had me."
"A minor point, I would have thought, considering how you turned out."
"Don't think I didn't ask my adviser when I found out you didn't even have to audit Beyond Temporal Mechanics. Q insisted that my dubious parentage actually made it mandatory that I complete several prerequisites most Q don't even have to endure."
"Don't call me that."
"It's your name."
"The rest of them can call me what they like but when it's just you and me . . ."
"Fine. Poor Amanda."
"Thank you, Junior."
"Don't ever . . . oh, never mind. I thought you would understand, but obviously . . ."
"No, I'm really curious. Her death is a fixed point in time. Meaning what?"
"In every conceivable timeline where she exists, she dies at roughly the same moment."
"Under the same circumstances?"
"For the most part."
"That sounds ominous."
"I know. There's actually a timeline where the evolved cube never makes it to the Alpha Quadrant and in that one she slips getting out of her bathtub and accidentally drowns."
"Now you're just teasing me."
"I'm not. It's like the multiverse has it in for her in a way I was always taught wasn't possible."
"Fixed points in time are big things, not small ones. They don't correlate to any individual mortal being's existence. All of the major worldwide wars on any planet, for example. Massive interstellar conflicts. The flashpoint in any given timeline may be slightly different, but with or without any individual's actions or lack thereof, fixed points in time occur anyway. They are part of the larger fabric of space-time, the culmination of energies and events that transcend what we normally think of as cause and effect."
"Thank you for the refresher course, but the concept is pretty much right there in the name: fixed point in time."
"What I'm saying is, there has never been an individual mortal's death, let alone a human's death, that qualified as a fixed point in time."
"And yet, hers is."
"And it gets worse."
"I'm pretty sure it wasn't always this way."
"But if it wasn't always this way, then that would mean there was a timeline where she didn't die, and if that was the case, you couldn't call her death a fixed point in time."
"What I'm saying is that now her death is a fixed point in time, but for most of my existence, I don't think that was the case."
"And how could you possibly know that?"
"I don't. It's just . . . a feeling."
"Did you ask your father about this?"
"And he told me to leave it alone. Sometimes things happen for reasons that are beyond our control and we are required to accept them."
"Your father said that."
"I know. Doesn't exactly sound like him, does it?"
"Your father? The Q who was kicked out of the Continuum for grossly abusing his powers how many times?"
"Yeah, but they always ask him to come back, don't they?"
"Wait ... we're Q, aren't we? The last time I checked we weren't required to accept anything. That's part of the whole omnipotent thing, isn't it?"
"He assured me that to intervene in any way in a fixed point in time such as this would inject so much chaos into the multiverse that even the entire Continuum might not be able to contain it."
"So, what are you going to do about it?"