That's actually a bug with SRB2 and not with ModernSonic. as for the homing attack coming to a stop after hitting a spring again, its an SRB2 bug as well. Though for enemies I don't get what the big deal is. It's like that in almost any game to feature the homing attack.
The thing is, almost any game to feature the homing attack also has the air dash. So that pretty much makes the stop when hitting an enemy a non issue. Colors and Forces are the only boost games where Sonic has a double jump.