Aella's disproportionate worry about a super-illegitimate heir to the throne

Aella would be in a good position vis-a-vis *any* illegitimate contenders. But Eric's case has so *many* aggravating features that Eric becomes, as it were super-duper illegitimate & so no real worry at all.

(i) Eric's illegitimate through the Queen - normally a much more tenuous case since the Queen herself is an outsider brought to the main line, i.e., brought in to marry the established heir. *Her* bastards are therefore normally complete blood-outsiders.
(ii) Eric's the product of rape not the Queen's love-child. Even if the Queen were a beloved figure, it's hard to imagine nobles or anyone else going to bat for a claim on Eric's behalf.
(iii) Eric's rapist father is none other than the Kingdom's mortal enemy, Ragar. There's therefore absolutely no chance he can become a popular figure in Northern England or have any sort of powerbase there.

Aella should just chill about multiply-illegitimate Eric. Of course Aella *might* want to end young Eric just because he's a damn Viking, but the film instead depicts Aella as worried about the lineal threat Eric could represent which is nuts.