Wind your neck in and step away from the conspiracy theories. It’s most likely a council being rubbish, possibly at the request the horse riders. As higgo says it’s not likely to be targeted to get you off the trails.
We’re (PMBA) trying to work with the equestrians to get sections of boggy bridleway surfaced so we can all use them, joint voice, more likely to get funding. In the meantime we’ve already managed to get some badly repaired sections sorted and other bits that were unrideable fixed. Ringing up and complaining proably won’t get you anywhere, maybe joining an access forum or organised group might (no promises though).
If the horsey lot are behind it, fair play to them for get organised and getting stuff done. If a few more mountain bikers organised we’d have more clout as well.