Should an amateur MMA competitor enter IBJJF rules competition at white belt?

Im organising a group of people entering a competition. An amateur MMA competitor who has had a fair few fights and is a very good grappler has started coming to the club. He wants to enter a competition under IBJJF rules and doesn’t know if he should enter at blue or white belt. He seems to think his home club said he should go at blue because of his background. I can’t find anything to say he can’t enter at white belt.

Morally, I feel blue is a good fit for him as he is very competent. Legitimately though I see no reason why he can’t do white as he is still learning the specific rule set.

Ive looked through IBJJF rules and can’t find anything to direct me (happy to be corrected). I’ve said he should do white category and see no actual problem with it.

Thoughts?