The same way that kernel developers of all kinds test drivers and software for which they have limited or no access: the users. At least in the minds of a very large company who seems to have been ticked off by a very small "company" with a leader like Theo.

Theo is a tool. A very intelligent tool, but still a tool. His attitude combined with the (apparent) project size of OpenBSD makes him easier to ignore.

Linus is a tool. A very intelligent tool, but still a tool. However, his project is large enough and has enough market impact that he's harder to ignore. Though his project is large enough that few outside of the developer community need to directly interact with him.

They both lack interpersonal communication skills. Which is fine for kernel development (except for those that have to work with them). They should realize this and either change their level of professionalism and tact, or not speak or interact directly with the public.

"The face you step on today may end up being the butt you have to kiss tomorrow."