1/4 oblivious transfer construction from 1/2?
No, your proposed alternative allows the attacker to deduce things beyond the value he selects.

For example, suppose that during his OT transfers, he decides to learn the values $s0$ and $s2$, allowing him to recover $m0 = c0 \oplus s0 \oplus s2$.  That is intended to be allowed, and so is fine as far as it goes.

However, the receiver can also deduce the value $m1 \oplus m2 \oplus m3 = c1 \oplus c2 \oplus c3 \oplus s0 \oplus s2$.  As the receiver is supposed to learn only the value he selected ($m0$ in this case), and nothing about the other messages, this is a violation of the OT properties.