That's wrong
Manufacturers such as Energica and BMW have proven that passive cooling (with air) is easy to implement and efficient. This does not require money or knowledge.
The main problem of Zero in fast loading is simply the tension !!! At 116 volts and over 7kW charging line just too much power is flowing that generates heat !!!
Money or knowledge, no, materials, space, and weight, yes. The cheapest energica is several grand more than the most expensive zero and their advertised range for "eco" mode is half of what zero says for city speeds. Their reported highway range is also about half of Zeros.
The i3 is extremely expensive for the range it provides as well.
I'm not saying zero cannot add thermal management, I'm saying that it would require a sacrifice in range, price, or both, and that zero is unlikely to take that tradeoff.
Is it "easy?" I suppose so, everything is relative. But no matter what your solution is, it's going to take up space and it's going to take up materials. Zero often pride themselves in having the most energy density, and they do that by cramming their batteries as close together with no active management. Without the bike getting bigger adding anything inbetween, even just channels for air, is going to take up space and lead to less cells in the monolith.
I'm not saying it isn't possible, I'm not even saying it's a bad idea, just that doing so would be against Zero's current strategy.