Do note that the Pour epoxies must have a lip to keep it from running off the sides, and the piece must be perfectly level.

Tape can be used, but if the tape bond fails, then you just made a big mess and have wasted product, and have to re do it. I have had little luck with the bartop pour epoxies and always wound up having to sand them flat and then polish them and have refused all future jobs in this realm.

Bartop epoxy also does not like UV light and will turn chalky if exposed to a lot of sunlight.

The darker spots on oak are very porous and sucks up a lot of stain deep into the wood. Even if you sand it, they will remain dark, so restaining and blending becomes necessary.

In your case I might just soak a Scotch brite pad with acetone or laquer thinner to remove the gummy exterior then use a polyurethane to refinish it with either a gloss/ semigloss or satin finish, whatever floats your boat.

It is really all up to how much effort you wish to expend on it.