IIRC lore explanation is that the Garleans can wiretap your linkshell communications, so saying sensitive mission details over the very easily intercepted linkshell comms is not great for keeping secret things secret. Thus, she only says 'pray return' on the LS, so that when you're there in person the details can be discussed in relative safety (which ends up not working out anyway as we got raided at the tender age of level 35)