I've worked as a consultant for years. I occasionally employ a lawyer to review contracts with my clients.
As a general rule of thumb, I'll only work for a client under one of three circumstances:
1. The client's standard contract is reasonable. This is rare.
2. The client's standard contract is unreasonable, but they're willing to cross-out or rewrite the objectionable bits before signing. This is very common.
3. It's worth everybody's time and money to get our respective lawyers involved. Hint: This will cost at least $1000 for each side, assuming 3 hours of legal time at roughly $300/hour.
This sort of email thread is one of several reasons I wouldn't touch a site like Gigster with a 10-foot pole. If I can't renegotiate an unreasonable contract, I'm not a respected consultant, I'm probably an interchangeable body.[1] If you can't afford three hours of your lawyer's time, you can't afford me.
The other reason why I wouldn't touch a site like Gigster is that those sites almost always turn into a race to the bottom for low-value jobs for the most difficult clients. It's OK to do a couple of those jobs when you're starting out—but once you've done real projects, your time is better spent networking to find new contacts.
[1] I might make exceptions for very large and established organizations, for the right project and budget.