What I like most about these free tax advice accountants are they will tell you form this or form that, but NEVER a single reference to ANY line of instruction on said forms which apply in any way to K-1 income withing a tax deferred account.
The instructions to Form 990T specifically state on page 1 (that is the first page - OK?) in the lower right corner that fiduciaries are responsible for filing Form 990T for paying taxes if UBTI is over $1000 on several types of tax exempt entities including Coverdell, Roth and regular IRAs and others.
Here is the cut and paste -
Fiduciaries for the following trusts that have $1,000 or more of unrelated trade or business gross income:
1. Individual retirement accounts (IRAs) described under section 408(a),
2. Simplified employee pensions (SEPs) described under section 408(k),
3. Simple incentive match plans (SIMPLEs) described under section 408(p),
4. Roth IRAs described under section 408A(b),
5. Coverdell education savings accounts (ESAs) described under section 530(b),
6. Archer medical savings accounts (Archer MSAs) described under section 220(d), and
7. Qualified tuition programs described under section 529
Since you seem unable to understand the instructions (understandable perhaps), why not just google "form 990 MLP IRA". You will find plenty of results with the first being a page from the site of the NAPTP (National Association of Publicly Traded Partnerships - of which this MLP is a member).