No, Mausoleum of the Emperor only works specifically for tribute summons. It says on Obelisk that you tribute to normal summon it. I know it's confusing but those are the rulings for those cards.
The only way Obelisk the Tormentor can be Normal Summoned is if you Tribute 3 monsters. Mausoleum can't do that. Even reducing Obelisk to Level 4 or lower doesn't stop it requiring 3 Tributes.
Anoymous
