I believe ur just trying to get somebody in trouble. I'm pretty sure you know what optifine is and saying he has another mod just because he has that... thats just stupid reasoning.
I don't think that SpoutCraft could be used as an example here, since last time I checked you can't download it as a mod, it's a client. And although SpoutCraft can be modded, it's mods aren't as wide-spread. Like, I've seen only a single mod for SpoutCraft.
Also, Spout isn't SpoutCraft. SpoutCraft is the client, Spout is the plugin.
It may be a client, but it is a modification of Minecraft itself, so my argument still works for the whole 'if one uses one mod/client he can use another'