Not true... Remember Tony C. of the Boston Red Sox? In 1969, he got beaned from the pitch of an Angels pitcher. Tony C. had a record of the most home runs hit before age 20...
Tony C was beaned Aug. 18, 1967. Previously, he’d been the youngest AL season home run champ and then he’d been the youngest American League player to reach 100 home runs at age 22.
https://en.wikipedia.org/wiki/Tony_Conigliaro
One extreme case does not prove that baseball is as dangerous as football across thousands of players.
However, for any promising young 2-sport star a large part of the decision ought to be which sport he really wants to devote himself to for the next 12-20 years. Considerations of money and injury risk may certainly enter into the deliberations, but he’d better think what he thinks he wants to be doing with his time and energies over many years. He should be a multi-millionaire in either case.