It's normal for some female monarchs to develop eggs in the winter along the Gulf coast,
south Atlantic coast and California coast even in locations where there is no milkweed. These females desperately want to find milkweed to lay their eggs on. Intentionally depriving them of milkweed (via cutting the milkweed down to the ground) will cause them alot of stress and they will end up dying without breeding. Providing these females with milkweed (any kind of milkweed) will give their offspring a chance to survive and contribute to the growth of future generations of monarchs.
Paradoxically, some of the same people who think its cruel for commercial butterfly breeders to ship monarchs to the northern states in the early Spring because there is no milkweed for them that early in the year, think its beneficial for home gardeners along the gulf coast to cut tropical milkweed to the ground in the late fall and winter even though the consequences are just as cruel: the females will frantically look for milkweed and die without breeding. Another irony is that far from harming the migratory instincts of the monarchs, the monarch migrations in Australia and New Zealand are actually 100% dependent on a evergreen tropical milkweed (Asclepias fruticosa) because that's the only kind of milkweed that grows at temperate zone latitudes in those countries. So monarch conservationists in those countries would never dream of cutting tropical milkweed down to the ground in the late fall and winter.