MarkB
Legend
Yeah, but those are two separate requirements. It can hear the caster because they're standing within 30 feet of it, and it can understand them because they're in telepathic communication with it.It shouldn't work.
Even if the PC had the means to telepathically communicate (bearing in mind only the Aboleth has telepathy and can stop listening at any time shutting the PC out from responding) the Aboleth needs to hear and understand the PC.
And sure, it could relinquish that communication, but from its viewpoint, why would it do so? It's not going to know it's in trouble within the time it takes to mentally project two monosyllabic words.