I offer toys to kids based on their and my personal preferences (not backed by research studies). Just like any other toys, Alien-based toys can be suitable for healthy playing for some 8-14-year-old children and not suitable for others. The short answer is "it depends" on the child.
Fictional material with high levels of gore and violence is generally considered as "nice tales for nice children" (Evans, 2014), and reading it as part of "normal development" (Tsitsani et al., 2012). See numerous examples of fairy tales, some cited below and others easily found elsewhere. The original "Alien" film has a total body count of 5 human crue members, 1 android and 1 alien - relatively low compared to, for example, an average book of Grimm’s Fairy Tales. Needless to say, fairy tale-based toys for 8-14-year-olds are widely available.
Non-fictional material, such as world history that covers wars, mass killings, slavery, etc, can have even higher levels of gore and violence. Yet, it is considered appropriate to teach in schools (I think, correctly, - again, not based on research evidence). For example, by age 14, the kids are often expected to know that millions of people died during WWII. Despite that, toy warriors from various ages are very common toys for 8-14-year-olds.
There is little evidence that I could find to show that not many children "in the target range of these toys [...] could have a healthy way to interact with" fairy tale-based toys or toy warriors.
Stephen Evans. (21 October 2014). BBC - Culture - Are Grimm’s Fairy Tales too twisted for children? : http://www.bbc.com/culture/story/20130801-too-grimm-for-children
On the covers are the most innocent of titles: Grimm’s Fairy Tales in
their English version or Children’s and Household Tales in the
original German editions published two hundred years ago. Nice tales
for nice children.
But behind the safe titles lie dark stories of sex and violence –
tales of murder, mutilation, cannibalism, infanticide and incest, as
one academic puts it. They are far from anything we might imagine as
acceptable today. If they were a video game, there would be calls to
Tsitsani P., Psyllidou S., Batzios S.P., Livas S., Ouranos M., Cassimos D. Fairy tales: a compass for children's healthy development--a qualitative study in a Greek island. Child Care Health Dev. 2012 Mar;38(2):266-72. doi: 10.1111/j.1365-2214.2011.01216.x. Epub 2011 Mar 6.
Four hundred and seventy parents took part in the study and were
interviewed following a semi-structured guide with open-ended trigger
questions. [...] The vast majority of interviewees acknowledged their
strong belief in the power of fairy tales and stated that their
children listen to stories at least once a week. Most of them use
storytelling as an instructive tool, in order to soothe their
children's anxieties or set examples for them. Concerning children's
preferences, the majority of them choose classic fairy tales over
modern ones with Little Red Riding Hood taking precedence over other
famous stories. All participants acknowledged the fact that their
children are amused and positively affected by storytelling, while
young readers share their enthusiasm for fairy tales in many ways,
mostly by talking about their favourite character. Finally, in
relation to the villains, children seem to be satisfied or relieved
when they are punished and only a small number of participants stated
that the cruel punishment of bad characters creates feelings of fear
to their kids. The findings of this study emphasize the crucial role
that storytelling plays in children's life and normal development.