You realize that Khornate succession is decided by combat correct?

If the current commander beat the predecessor it meant that he was MORE cunning and brutal than the one before him. In an orky sense at the very least.

Also again, 40k ships have A LOT of guns and are designed to fill area's with huge amounts of devastating firepower.

Given the stated personality of the RT as well (A risk taker, and a man who loves to dance on fate's feet. Given by his previous behavior in handling the Forge World fleet.), I doubt he'd be the type to hang back and flit around as well, and then with the telepathic motivation to get in close and duke it out I'd expect more of a "FTL in close, and try and hit them with a full broadside at point blank.", only to find out that these cruisers being so heavy can not only take it, but also that there's now a full staff of Khronate Berserkers on his bridge asking for his blood type.

And the Khornate Fleet has enough heavy cruisers to make a formation that covers any angle of approach, they do have prow guns, aft guns, starboard guns, deck guns, etc. These are vehicles made for space.