The minimum initial deposit of $2,000 needs to stay in the account for two business days after initial funding, to get the account activated properly. Once the account is activated, the account balance can go below $2,000. You will not be able to use margin at any time that the account is below $2,000.
In a margin account, you should be able to transfer funds immediately, especially when you are transferring from one account to another account at the same brokerage, without having to wait for three day settlement.
IB doesn't want to get into trouble, these days that the SEC and every other federal agency are going over everything with a finetooth comb. The federal agencies are highly interested in snooping out anything that might be even slightly perceived as deceptive and fraudulent activity. Everything, except for the one glaring fraudulent example of election tampering. Is there a connection? Is all this anti-fraud scrutiny merely an attempt by the biggest most corrupt fraud of all to distract all attention from itself? You bet it is.
In the meantime, IB doesn't want to get into any hot water. Can't blame them. We can work around these restrictions, but we will have to be more quiet about it. Just don't make yourself obvious.