RAW; maybe. Intent; yes. Balance; no.
That is to say, the Siren's Summon is not a Mark of Chaos, it is an ability available to ships in a Slaaneshi fleet that already have the mark. Given that Marks of Chaos are specifically allowed to function while spectral the implication is that things not specifically mentioned don't function. This isn't necessarily the case though, as the Siren's Summon doesn't appear amongst the list of specifically prohibited options either. So we don't know if all things bar the listed exceptions are allowed or all things bar the listed exceptions are disallowed.
I would say that the mechanic which allows the function of the Mark of Slaanesh would work equally for the Siren's Summon. Therefore I find it harder to justify an argument for the "whatever is not specifically mentioned is disallowed" stance.
In terms of balance though, I think this is a bit strong. No BFI, no RO, no LO, no asteroid/warp rift navigation test ...
In short, there's nothing to say you couldn't use it to full effect on a daemonship.
