Giving a huge number of merits to one post may have side effects.
Your intentions may be good and you want to help him to rank up,
but, as you said, 90% of users will think it is your alt and such they will avoid dealing with him.

If he was able to create such valuable post, he probably has many of them, you can give few merits to each one.

If I may ask: why do you want to get rid of your sMerits?
just keep them and whenever you find a good post, give it the amount it deserves.

Sending merits can't be reverted, what if you give all your sMerits to one user than discover that his post was copy pasted from someone else!!