"Legitimized" != "got famous"
So a hundred thousand more people saw Randy whoop Tito than saw Randy whoop Chuck. Whoopdy-fucking-doo.
But yes, Tito (with the greater drawing power of Ken Shamrock) kept the UFC on life support long enough to get to TUF. Yaay Tito. I'm not saying Tito was irrelevant. I'm saying let's not blow his role out of proportion.
If you look at the buyrates between UFC 40 and TUF, the picture is not quite so clear. ie. the last Tito card before TUF did 40k. While Mir/Sylvia (with a Shamrock/Kimo co-main) did 110k. It suggests, perhaps, that it was Ken's pro-wrestling fanbase, rather than Tito, that was to be credited for the post 40 success.
FACT #2(a): sporting-wise, Tito has been irrelevant to the division since 2006 (SD over Forrest.)
FACT #2(b): business-wise, Tito has been irrelevant to the sport since, at best, 2007 (UFC 73: stacked, Tito/Rashad I)