That makes it sounds more dramatic than it is. Stallman is an idealist and attaches moral value to the licensing of code. Torvalds is an engineer and just wants to ship code. His license of choice matches his model for doing this.
Basically Stallman is ideologically opposed to the existence of proprietary software and Torvalds is fine with a mixture of free/open software mixed with proprietary software.
The two of them are often mentioned together because the largest results of their labours (the GNU userland and the linux kernel) are combined to form 'linux based distributions', generally just referred to as 'Linux' (or 'GNU/Linux' as Stallman insists, because he justifiably wants some more public recognition of the impact of his project even if that just isn't the way things work).
Considering their differences and the way in which their works are combined it shouldn't be that surprising that there's some friction and snarky comments that spill out from time to time.