I'm not sure we've had precisely this issue raised before, Morbius. But, as MK and Trex suggest, I haven't felt able to rely on any cut and dried rules in deciding on some questions regarding plurals.
At one end of the spectrum is wolves. There is a rare verb wolve, meaning to behave like a wolf, or, of an organ, to make a wolf-like sound. Wolve is allowed in Chihuahua, but so is wolves, since anyone thinking of the word is almost certain to think of it as the plural of wolf.
I can't actually think of an example at the other extreme. That would be a word ending in -ves that is overwhelmingly used as an inflected form of a word ending in -ve, though it is also an obscure inflected form of a word ending in -f or -fe.
The case you raise, lives, is somewhere in the middle. If we allowed it, is there a danger that a lot of players, on seeing the word in a solution, would be bemused, thinking only of the verb (rhyming with gives) and not of the noun (rhyming with hives)? I'll come back to this question when I've had a chance to do some investigation. As MK mentioned, there would be a number of other words raising similar issues. In fact, there are some that almost certainly should be changed. I was planning to use wives as an example of a word that obviously should be allowed, until I discovered that it isn't! So I used wolves as my example. But it does seem wrong to rule out wives because of the rare verb wive.