i dont think sabotaging blood elven arcane sanctums and sending in a dwarven spy to get intel on key parts of silvermoon to destroy count as
"checking them out".
as a blood elf playing through the starter zone they dont pick a side until the dwarves and the night elves attack them, and then the forsaken help them.
if the dwarves and night elves hadnt attacked them its likely the blood elves wouldve rejoined the alliance or atleast wouldve remained neutral