asked my manager and he agreed that it sounded like a historical figure, but didn't know anyone specific.
it's a surname and the tsune means "always".
other "matsu" names:

akamatsu - red pine
matsubayashi - pine forest
matsu takako - my favourite actress
matsushima - pine island (famous tourist area near sendai)

there are millions more. maybe someone who knows japanese history (i don't) can help with who this spell check person is. (i doubt it's a rock star!)