Though more because the lines

Sometimes I wish that I could stop you from talking
when I hear the silly things that you say.
I think somebody better put out the big light,
'cause I can't stand to see you this way.

you might also note a intriguing verb in between the chorus's two repetitions of 'Alison' as the chords staccato-stagger upwards: I know this world is killing you...

I've never made that interpretation nor heard of anyone else making such an interpretation.
It contradicts the chorus as I've always read it:
"Alison, I know this world is killing you,
Alison, my aim is true"
I read that as Elvis saying his love can save her from the bad things in the world, not that he wants to bring about her demise.

It reminds me of an interpretation of Townes van Zandt's Pancho and Lefty that I read in No Depression earlier this year. This person saw it as a song about a friendship that came to an end with Pancho's death, but not that Lefty had killed him. Which would suggest he died at the hands of the Federales, even though the lyric says they "let him slip away".
I can't see how that interpretation works with lines like "the dust that Pancho bit down south, Ended up in Lefty's mouth" or "The day they laid poor Pancho low, Lefty split for Ohio, Where he got the bread to go, There ain't nobody knows." as well as "He only did what he had to do"

Still, is my interpretation any more valid than anyone else's with such an elliptical song.

I've never seen it as a threat. More of a statement that he thinks he was right and that Alison will, in time, see the error of her ways. In all the times I've heard Elvis sing it on record and live I think that he invests the phrase with tenderness and regret and wounded pride (he used to combine Alison it with John Hiatt's 'Living just a little' with it's line about 'deep down inside there's an ember of pride'). With regard to the putting out the big light I've seen this as a potential act of self slaughter in reponse to the heart-ache and the thousand natural shocks that (this too, too sullied) flesh is heir to.

him saying that he'd be the one for her. Earlier in the song he talks about his pal who copped off with her and then he suggests an unhappy marriage so I took "My aim is true" as meaning he wouldn't let her down.

...were it not for "I think somebody better put out the big light". The chorus could easily be interpreted as a sort of tender "I've got your number, my girl" quite easily, but I'm sticking with the "wants her dead" interpretation, which was my feeling about the song from pretty much the second or third time I ever heard it.

I know EC has disavowed this view, btw, but I wonder if that's not to do with trying to avoid accusations of misogyny.

Who knows?

into 'He'll Have To Go'

Put your sweet lips a little closer to the phone
Just pretend that we're together all alone
Tell the man to turn the juke box way down low
You can tell your friend there with you, he'll have to go

You can't say the words I want to hear
When you're with another man
If you love me, answer yes or no
Darling I will understand

which seems to back up the 'kick him to the kerb, girlfriend, come see about me' POV

Although he once said if anyone ever concluded a review with the line 'Costello's aim is still true' again he would cheerful strangle them

It never struck me as a threat, I have to say. At least, not an explicit one. Just a frustration at the fact that she's off with someone else.